an example of a journal article review

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Education and Communications
Critical Reviews

How to Write an Article Review (With Examples)

Last Updated: April 24, 2024 Fact Checked

Preparing to Write Your Review

Writing the article review, sample article reviews, expert q&a.

This article was co-authored by Jake Adams . Jake Adams is an academic tutor and the owner of Simplifi EDU, a Santa Monica, California based online tutoring business offering learning resources and online tutors for academic subjects K-College, SAT & ACT prep, and college admissions applications. With over 14 years of professional tutoring experience, Jake is dedicated to providing his clients the very best online tutoring experience and access to a network of excellent undergraduate and graduate-level tutors from top colleges all over the nation. Jake holds a BS in International Business and Marketing from Pepperdine University. There are 12 references cited in this article, which can be found at the bottom of the page. This article has been fact-checked, ensuring the accuracy of any cited facts and confirming the authority of its sources. This article has been viewed 3,102,573 times.

An article review is both a summary and an evaluation of another writer's article. Teachers often assign article reviews to introduce students to the work of experts in the field. Experts also are often asked to review the work of other professionals. Understanding the main points and arguments of the article is essential for an accurate summation. Logical evaluation of the article's main theme, supporting arguments, and implications for further research is an important element of a review . Here are a few guidelines for writing an article review.

Education specialist Alexander Peterman recommends: "In the case of a review, your objective should be to reflect on the effectiveness of what has already been written, rather than writing to inform your audience about a subject."

Article Review 101

Read the article very closely, and then take time to reflect on your evaluation. Consider whether the article effectively achieves what it set out to.
Write out a full article review by completing your intro, summary, evaluation, and conclusion. Don't forget to add a title, too!
Proofread your review for mistakes (like grammar and usage), while also cutting down on needless information.

Step 1 Understand what an article review is.

Article reviews present more than just an opinion. You will engage with the text to create a response to the scholarly writer's ideas. You will respond to and use ideas, theories, and research from your studies. Your critique of the article will be based on proof and your own thoughtful reasoning.
An article review only responds to the author's research. It typically does not provide any new research. However, if you are correcting misleading or otherwise incorrect points, some new data may be presented.
An article review both summarizes and evaluates the article.

Step 2 Think about the organization of the review article.

Summarize the article. Focus on the important points, claims, and information.
Discuss the positive aspects of the article. Think about what the author does well, good points she makes, and insightful observations.
Identify contradictions, gaps, and inconsistencies in the text. Determine if there is enough data or research included to support the author's claims. Find any unanswered questions left in the article.

Make note of words or issues you don't understand and questions you have.
Look up terms or concepts you are unfamiliar with, so you can fully understand the article. Read about concepts in-depth to make sure you understand their full context.

Pay careful attention to the meaning of the article. Make sure you fully understand the article. The only way to write a good article review is to understand the article.

With either method, make an outline of the main points made in the article and the supporting research or arguments. It is strictly a restatement of the main points of the article and does not include your opinions.
After putting the article in your own words, decide which parts of the article you want to discuss in your review. You can focus on the theoretical approach, the content, the presentation or interpretation of evidence, or the style. You will always discuss the main issues of the article, but you can sometimes also focus on certain aspects. This comes in handy if you want to focus the review towards the content of a course.
Review the summary outline to eliminate unnecessary items. Erase or cross out the less important arguments or supplemental information. Your revised summary can serve as the basis for the summary you provide at the beginning of your review.

Step 6 Write an outline of your evaluation.

What does the article set out to do?
What is the theoretical framework or assumptions?
Are the central concepts clearly defined?
How adequate is the evidence?
How does the article fit into the literature and field?
Does it advance the knowledge of the subject?
How clear is the author's writing? Don't: include superficial opinions or your personal reaction. Do: pay attention to your biases, so you can overcome them.

For example, in MLA , a citation may look like: Duvall, John N. "The (Super)Marketplace of Images: Television as Unmediated Mediation in DeLillo's White Noise ." Arizona Quarterly 50.3 (1994): 127-53. Print. [9] X Trustworthy Source Purdue Online Writing Lab Trusted resource for writing and citation guidelines Go to source

For example: The article, "Condom use will increase the spread of AIDS," was written by Anthony Zimmerman, a Catholic priest.

Your introduction should only be 10-25% of your review.
End the introduction with your thesis. Your thesis should address the above issues. For example: Although the author has some good points, his article is biased and contains some misinterpretation of data from others’ analysis of the effectiveness of the condom.

Use direct quotes from the author sparingly.
Review the summary you have written. Read over your summary many times to ensure that your words are an accurate description of the author's article.

Support your critique with evidence from the article or other texts.
The summary portion is very important for your critique. You must make the author's argument clear in the summary section for your evaluation to make sense.
Remember, this is not where you say if you liked the article or not. You are assessing the significance and relevance of the article.
Use a topic sentence and supportive arguments for each opinion. For example, you might address a particular strength in the first sentence of the opinion section, followed by several sentences elaborating on the significance of the point.

This should only be about 10% of your overall essay.
For example: This critical review has evaluated the article "Condom use will increase the spread of AIDS" by Anthony Zimmerman. The arguments in the article show the presence of bias, prejudice, argumentative writing without supporting details, and misinformation. These points weaken the author’s arguments and reduce his credibility.

Make sure you have identified and discussed the 3-4 key issues in the article.

↑ https://libguides.cmich.edu/writinghelp/articlereview
↑ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4548566/
↑ Jake Adams. Academic Tutor & Test Prep Specialist. Expert Interview. 24 July 2020.
↑ https://guides.library.queensu.ca/introduction-research/writing/critical
↑ https://www.iup.edu/writingcenter/writing-resources/organization-and-structure/creating-an-outline.html
↑ https://writing.umn.edu/sws/assets/pdf/quicktips/titles.pdf
↑ https://owl.purdue.edu/owl/research_and_citation/mla_style/mla_formatting_and_style_guide/mla_works_cited_periodicals.html
↑ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4548565/
↑ https://writingcenter.uconn.edu/wp-content/uploads/sites/593/2014/06/How_to_Summarize_a_Research_Article1.pdf
↑ https://www.uis.edu/learning-hub/writing-resources/handouts/learning-hub/how-to-review-a-journal-article
↑ https://writingcenter.unc.edu/tips-and-tools/editing-and-proofreading/

About This Article

If you have to write an article review, read through the original article closely, taking notes and highlighting important sections as you read. Next, rewrite the article in your own words, either in a long paragraph or as an outline. Open your article review by citing the article, then write an introduction which states the article’s thesis. Next, summarize the article, followed by your opinion about whether the article was clear, thorough, and useful. Finish with a paragraph that summarizes the main points of the article and your opinions. To learn more about what to include in your personal critique of the article, keep reading the article! Did this summary help you? Yes No

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What is an ahk file, keeping yourself safe in college: everything you need to know, myths about online high schools: everything you need to know, reasons you should study geography: everything you need to know, the vtoman jump 1800 portable power station: the best of the best, key roles of a school superintendent: everything you need to know, is earning a degree online worthwhile and beneficial, why learners cheat: everything you need to know, top issues in education: everything you need to know, how to write an article review (with sample reviews) .

An article review is a critical evaluation of a scholarly or scientific piece, which aims to summarize its main ideas, assess its contributions, and provide constructive feedback. A well-written review not only benefits the author of the article under scrutiny but also serves as a valuable resource for fellow researchers and scholars. Follow these steps to create an effective and informative article review:

1. Understand the purpose: Before diving into the article, it is important to understand the intent of writing a review. This helps in focusing your thoughts, directing your analysis, and ensuring your review adds value to the academic community.

2. Read the article thoroughly: Carefully read the article multiple times to get a complete understanding of its content, arguments, and conclusions. As you read, take notes on key points, supporting evidence, and any areas that require further exploration or clarification.

3. Summarize the main ideas: In your review’s introduction, briefly outline the primary themes and arguments presented by the author(s). Keep it concise but sufficiently informative so that readers can quickly grasp the essence of the article.

4. Evaluate the strengths and weaknesses: In subsequent paragraphs, assess the strengths and limitations of the article based on factors such as methodology, quality of evidence presented, coherence of arguments, and alignment with existing literature in the field. Be fair and objective while providing your critique.

5. Discuss any implications: Deliberate on how this particular piece contributes to or challenges existing knowledge in its discipline. You may also discuss potential improvements for future research or explore real-world applications stemming from this study.

6. Provide recommendations: Finally, offer suggestions for both the author(s) and readers regarding how they can further build on this work or apply its findings in practice.

7. Proofread and revise: Once your initial draft is complete, go through it carefully for clarity, accuracy, and coherence. Revise as necessary, ensuring your review is both informative and engaging for readers.

Sample Review:

A Critical Review of “The Effects of Social Media on Mental Health”

Introduction:

“The Effects of Social Media on Mental Health” is a timely article which investigates the relationship between social media usage and psychological well-being. The authors present compelling evidence to support their argument that excessive use of social media can result in decreased self-esteem, increased anxiety, and a negative impact on interpersonal relationships.

Strengths and weaknesses:

One of the strengths of this article lies in its well-structured methodology utilizing a variety of sources, including quantitative surveys and qualitative interviews. This approach provides a comprehensive view of the topic, allowing for a more nuanced understanding of the effects of social media on mental health. However, it would have been beneficial if the authors included a larger sample size to increase the reliability of their conclusions. Additionally, exploring how different platforms may influence mental health differently could have added depth to the analysis.

Implications:

The findings in this article contribute significantly to ongoing debates surrounding the psychological implications of social media use. It highlights the potential dangers that excessive engagement with online platforms may pose to one’s mental well-being and encourages further research into interventions that could mitigate these risks. The study also offers an opportunity for educators and policy-makers to take note and develop strategies to foster healthier online behavior.

Recommendations:

Future researchers should consider investigating how specific social media platforms impact mental health outcomes, as this could lead to more targeted interventions. For practitioners, implementing educational programs aimed at promoting healthy online habits may be beneficial in mitigating the potential negative consequences associated with excessive social media use.

Conclusion:

Overall, “The Effects of Social Media on Mental Health” is an important and informative piece that raises awareness about a pressing issue in today’s digital age. Given its minor limitations, it provides valuable

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How to Review a Journal Article

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For many kinds of assignments, like a literature review , you may be asked to offer a critique or review of a journal article. This is an opportunity for you as a scholar to offer your qualified opinion and evaluation of how another scholar has composed their article, argument, and research. That means you will be expected to go beyond a simple summary of the article and evaluate it on a deeper level. As a college student, this might sound intimidating. However, as you engage with the research process, you are becoming immersed in a particular topic, and your insights about the way that topic is presented are valuable and can contribute to the overall conversation surrounding your topic.

IMPORTANT NOTE!!

Some disciplines, like Criminal Justice, may only want you to summarize the article without including your opinion or evaluation. If your assignment is to summarize the article only, please see our literature review handout.

Before getting started on the critique, it is important to review the article thoroughly and critically. To do this, we recommend take notes, annotating , and reading the article several times before critiquing. As you read, be sure to note important items like the thesis, purpose, research questions, hypotheses, methods, evidence, key findings, major conclusions, tone, and publication information. Depending on your writing context, some of these items may not be applicable.

Questions to Consider

To evaluate a source, consider some of the following questions. They are broken down into different categories, but answering these questions will help you consider what areas to examine. With each category, we recommend identifying the strengths and weaknesses in each since that is a critical part of evaluation.

Evaluating Purpose and Argument

How well is the purpose made clear in the introduction through background/context and thesis?
How well does the abstract represent and summarize the article’s major points and argument?
How well does the objective of the experiment or of the observation fill a need for the field?
How well is the argument/purpose articulated and discussed throughout the body of the text?
How well does the discussion maintain cohesion?

Evaluating the Presentation/Organization of Information

How appropriate and clear is the title of the article?
Where could the author have benefited from expanding, condensing, or omitting ideas?
How clear are the author’s statements? Challenge ambiguous statements.
What underlying assumptions does the author have, and how does this affect the credibility or clarity of their article?
How objective is the author in his or her discussion of the topic?
How well does the organization fit the article’s purpose and articulate key goals?

Evaluating Methods

How appropriate are the study design and methods for the purposes of the study?
How detailed are the methods being described? Is the author leaving out important steps or considerations?
Have the procedures been presented in enough detail to enable the reader to duplicate them?

Evaluating Data

Scan and spot-check calculations. Are the statistical methods appropriate?
Do you find any content repeated or duplicated?
How many errors of fact and interpretation does the author include? (You can check on this by looking up the references the author cites).
What pertinent literature has the author cited, and have they used this literature appropriately?

Following, we have an example of a summary and an evaluation of a research article. Note that in most literature review contexts, the summary and evaluation would be much shorter. This extended example shows the different ways a student can critique and write about an article.

Chik, A. (2012). Digital gameplay for autonomous foreign language learning: Gamers’ and language teachers’ perspectives. In H. Reinders (ed.), Digital games in language learning and teaching (pp. 95-114). Eastbourne, UK: Palgrave Macmillan.

Be sure to include the full citation either in a reference page or near your evaluation if writing an annotated bibliography .

In Chik’s article “Digital Gameplay for Autonomous Foreign Language Learning: Gamers’ and Teachers’ Perspectives”, she explores the ways in which “digital gamers manage gaming and gaming-related activities to assume autonomy in their foreign language learning,” (96) which is presented in contrast to how teachers view the “pedagogical potential” of gaming. The research was described as an “umbrella project” consisting of two parts. The first part examined 34 language teachers’ perspectives who had limited experience with gaming (only five stated they played games regularly) (99). Their data was recorded through a survey, class discussion, and a seven-day gaming trial done by six teachers who recorded their reflections through personal blog posts. The second part explored undergraduate gaming habits of ten Hong Kong students who were regular gamers. Their habits were recorded through language learning histories, videotaped gaming sessions, blog entries of gaming practices, group discussion sessions, stimulated recall sessions on gaming videos, interviews with other gamers, and posts from online discussion forums. The research shows that while students recognize the educational potential of games and have seen benefits of it in their lives, the instructors overall do not see the positive impacts of gaming on foreign language learning.

The summary includes the article’s purpose, methods, results, discussion, and citations when necessary.

This article did a good job representing the undergraduate gamers’ voices through extended quotes and stories. Particularly for the data collection of the undergraduate gamers, there were many opportunities for an in-depth examination of their gaming practices and histories. However, the representation of the teachers in this study was very uneven when compared to the students. Not only were teachers labeled as numbers while the students picked out their own pseudonyms, but also when viewing the data collection, the undergraduate students were more closely examined in comparison to the teachers in the study. While the students have fifteen extended quotes describing their experiences in their research section, the teachers only have two of these instances in their section, which shows just how imbalanced the study is when presenting instructor voices.

Some research methods, like the recorded gaming sessions, were only used with students whereas teachers were only asked to blog about their gaming experiences. This creates a richer narrative for the students while also failing to give instructors the chance to have more nuanced perspectives. This lack of nuance also stems from the emphasis of the non-gamer teachers over the gamer teachers. The non-gamer teachers’ perspectives provide a stark contrast to the undergraduate gamer experiences and fits neatly with the narrative of teachers not valuing gaming as an educational tool. However, the study mentioned five teachers that were regular gamers whose perspectives are left to a short section at the end of the presentation of the teachers’ results. This was an opportunity to give the teacher group a more complex story, and the opportunity was entirely missed.

Additionally, the context of this study was not entirely clear. The instructors were recruited through a master’s level course, but the content of the course and the institution’s background is not discussed. Understanding this context helps us understand the course’s purpose(s) and how those purposes may have influenced the ways in which these teachers interpreted and saw games. It was also unclear how Chik was connected to this masters’ class and to the students. Why these particular teachers and students were recruited was not explicitly defined and also has the potential to skew results in a particular direction.

Overall, I was inclined to agree with the idea that students can benefit from language acquisition through gaming while instructors may not see the instructional value, but I believe the way the research was conducted and portrayed in this article made it very difficult to support Chik’s specific findings.

Some professors like you to begin an evaluation with something positive but isn’t always necessary.

The evaluation is clearly organized and uses transitional phrases when moving to a new topic.

This evaluation includes a summative statement that gives the overall impression of the article at the end, but this can also be placed at the beginning of the evaluation.

This evaluation mainly discusses the representation of data and methods. However, other areas, like organization, are open to critique.

How to Write an Article Review: Tips and Examples

Did you know that article reviews are not just academic exercises but also a valuable skill in today's information age? In a world inundated with content, being able to dissect and evaluate articles critically can help you separate the wheat from the chaff. Whether you're a student aiming to excel in your coursework or a professional looking to stay well-informed, mastering the art of writing article reviews is an invaluable skill.

Short Description

In this article, our research paper writing service experts will start by unraveling the concept of article reviews and discussing the various types. You'll also gain insights into the art of formatting your review effectively. To ensure you're well-prepared, we'll take you through the pre-writing process, offering tips on setting the stage for your review. But it doesn't stop there. You'll find a practical example of an article review to help you grasp the concepts in action. To complete your journey, we'll guide you through the post-writing process, equipping you with essential proofreading techniques to ensure your work shines with clarity and precision!

What Is an Article Review: Grasping the Concept

A review article is a type of professional paper writing that demands a high level of in-depth analysis and a well-structured presentation of arguments. It is a critical, constructive evaluation of literature in a particular field through summary, classification, analysis, and comparison.

If you write a scientific review, you have to use database searches to portray the research. Your primary goal is to summarize everything and present a clear understanding of the topic you've been working on.

Writing Involves:

Summarization, classification, analysis, critiques, and comparison.
The analysis, evaluation, and comparison require the use of theories, ideas, and research relevant to the subject area of the article.
It is also worth nothing if a review does not introduce new information, but instead presents a response to another writer's work.
Check out other samples to gain a better understanding of how to review the article.

Types of Review

When it comes to article reviews, there's more than one way to approach the task. Understanding the various types of reviews is like having a versatile toolkit at your disposal. In this section, we'll walk you through the different dimensions of review types, each offering a unique perspective and purpose. Whether you're dissecting a scholarly article, critiquing a piece of literature, or evaluating a product, you'll discover the diverse landscape of article reviews and how to navigate it effectively.

Journal Article Review

Just like other types of reviews, a journal article review assesses the merits and shortcomings of a published work. To illustrate, consider a review of an academic paper on climate change, where the writer meticulously analyzes and interprets the article's significance within the context of environmental science.

Research Article Review

Distinguished by its focus on research methodologies, a research article review scrutinizes the techniques used in a study and evaluates them in light of the subsequent analysis and critique. For instance, when reviewing a research article on the effects of a new drug, the reviewer would delve into the methods employed to gather data and assess their reliability.

Science Article Review

In the realm of scientific literature, a science article review encompasses a wide array of subjects. Scientific publications often provide extensive background information, which can be instrumental in conducting a comprehensive analysis. For example, when reviewing an article about the latest breakthroughs in genetics, the reviewer may draw upon the background knowledge provided to facilitate a more in-depth evaluation of the publication.

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Formatting an Article Review

The format of the article should always adhere to the citation style required by your professor. If you're not sure, seek clarification on the preferred format and ask him to clarify several other pointers to complete the formatting of an article review adequately.

How Many Publications Should You Review?

In what format should you cite your articles (MLA, APA, ASA, Chicago, etc.)?
What length should your review be?
Should you include a summary, critique, or personal opinion in your assignment?
Do you need to call attention to a theme or central idea within the articles?
Does your instructor require background information?

When you know the answers to these questions, you may start writing your assignment. Below are examples of MLA and APA formats, as those are the two most common citation styles.

Using the APA Format

Articles appear most commonly in academic journals, newspapers, and websites. If you write an article review in the APA format, you will need to write bibliographical entries for the sources you use:

Web : Author [last name], A.A [first and middle initial]. (Year, Month, Date of Publication). Title. Retrieved from {link}
Journal : Author [last name], A.A [first and middle initial]. (Publication Year). Publication Title. Periodical Title, Volume(Issue), pp.-pp.
Newspaper : Author [last name], A.A [first and middle initial]. (Year, Month, Date of Publication). Publication Title. Magazine Title, pp. xx-xx.

Using MLA Format

Web : Last, First Middle Initial. “Publication Title.” Website Title. Website Publisher, Date Month Year Published. Web. Date Month Year Accessed.
Newspaper : Last, First M. “Publication Title.” Newspaper Title [City] Date, Month, Year Published: Page(s). Print.
Journal : Last, First M. “Publication Title.” Journal Title Series Volume. Issue (Year Published): Page(s). Database Name. Web. Date Month Year Accessed.

Enhance your writing effortlessly with EssayPro.com , where you can order an article review or any other writing task. Our team of expert writers specializes in various fields, ensuring your work is not just summarized, but deeply analyzed and professionally presented. Ideal for students and professionals alike, EssayPro offers top-notch writing assistance tailored to your needs. Elevate your writing today with our skilled team at your article review writing service !

The Pre-Writing Process

Facing this task for the first time can really get confusing and can leave you unsure of where to begin. To create a top-notch article review, start with a few preparatory steps. Here are the two main stages from our dissertation services to get you started:

Step 1: Define the right organization for your review. Knowing the future setup of your paper will help you define how you should read the article. Here are the steps to follow:

Summarize the article — seek out the main points, ideas, claims, and general information presented in the article.
Define the positive points — identify the strong aspects, ideas, and insightful observations the author has made.
Find the gaps —- determine whether or not the author has any contradictions, gaps, or inconsistencies in the article and evaluate whether or not he or she used a sufficient amount of arguments and information to support his or her ideas.
Identify unanswered questions — finally, identify if there are any questions left unanswered after reading the piece.

Step 2: Move on and review the article. Here is a small and simple guide to help you do it right:

Start off by looking at and assessing the title of the piece, its abstract, introductory part, headings and subheadings, opening sentences in its paragraphs, and its conclusion.
First, read only the beginning and the ending of the piece (introduction and conclusion). These are the parts where authors include all of their key arguments and points. Therefore, if you start with reading these parts, it will give you a good sense of the author's main points.
Finally, read the article fully.

These three steps make up most of the prewriting process. After you are done with them, you can move on to writing your own review—and we are going to guide you through the writing process as well.

Outline and Template

As you progress with reading your article, organize your thoughts into coherent sections in an outline. As you read, jot down important facts, contributions, or contradictions. Identify the shortcomings and strengths of your publication. Begin to map your outline accordingly.

If your professor does not want a summary section or a personal critique section, then you must alleviate those parts from your writing. Much like other assignments, an article review must contain an introduction, a body, and a conclusion. Thus, you might consider dividing your outline according to these sections as well as subheadings within the body. If you find yourself troubled with the pre-writing and the brainstorming process for this assignment, seek out a sample outline.

Your custom essay must contain these constituent parts:

Pre-Title Page - Before diving into your review, start with essential details: article type, publication title, and author names with affiliations (position, department, institution, location, and email). Include corresponding author info if needed.
Running Head - In APA format, use a concise title (under 40 characters) to ensure consistent formatting.
Summary Page - Optional but useful. Summarize the article in 800 words, covering background, purpose, results, and methodology, avoiding verbatim text or references.
Title Page - Include the full title, a 250-word abstract, and 4-6 keywords for discoverability.
Introduction - Set the stage with an engaging overview of the article.
Body - Organize your analysis with headings and subheadings.
Works Cited/References - Properly cite all sources used in your review.
Optional Suggested Reading Page - If permitted, suggest further readings for in-depth exploration.
Tables and Figure Legends (if instructed by the professor) - Include visuals when requested by your professor for clarity.

Example of an Article Review

You might wonder why we've dedicated a section of this article to discuss an article review sample. Not everyone may realize it, but examining multiple well-constructed examples of review articles is a crucial step in the writing process. In the following section, our essay writing service experts will explain why.

Looking through relevant article review examples can be beneficial for you in the following ways:

To get you introduced to the key works of experts in your field.
To help you identify the key people engaged in a particular field of science.
To help you define what significant discoveries and advances were made in your field.
To help you unveil the major gaps within the existing knowledge of your field—which contributes to finding fresh solutions.
To help you find solid references and arguments for your own review.
To help you generate some ideas about any further field of research.
To help you gain a better understanding of the area and become an expert in this specific field.
To get a clear idea of how to write a good review.

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Steps for Writing an Article Review

Here is a guide with critique paper format on how to write a review paper:

Step 1: Write the Title

First of all, you need to write a title that reflects the main focus of your work. Respectively, the title can be either interrogative, descriptive, or declarative.

Step 2: Cite the Article

Next, create a proper citation for the reviewed article and input it following the title. At this step, the most important thing to keep in mind is the style of citation specified by your instructor in the requirements for the paper. For example, an article citation in the MLA style should look as follows:

Author's last and first name. "The title of the article." Journal's title and issue(publication date): page(s). Print

Abraham John. "The World of Dreams." Virginia Quarterly 60.2(1991): 125-67. Print.

Step 3: Article Identification

After your citation, you need to include the identification of your reviewed article:

Title of the article
Title of the journal
Year of publication

All of this information should be included in the first paragraph of your paper.

The report "Poverty increases school drop-outs" was written by Brian Faith – a Health officer – in 2000.

Step 4: Introduction

Your organization in an assignment like this is of the utmost importance. Before embarking on your writing process, you should outline your assignment or use an article review template to organize your thoughts coherently.

If you are wondering how to start an article review, begin with an introduction that mentions the article and your thesis for the review.
Follow up with a summary of the main points of the article.
Highlight the positive aspects and facts presented in the publication.
Critique the publication by identifying gaps, contradictions, disparities in the text, and unanswered questions.

Step 5: Summarize the Article

Make a summary of the article by revisiting what the author has written about. Note any relevant facts and findings from the article. Include the author's conclusions in this section.

Step 6: Critique It

Present the strengths and weaknesses you have found in the publication. Highlight the knowledge that the author has contributed to the field. Also, write about any gaps and/or contradictions you have found in the article. Take a standpoint of either supporting or not supporting the author's assertions, but back up your arguments with facts and relevant theories that are pertinent to that area of knowledge. Rubrics and templates can also be used to evaluate and grade the person who wrote the article.

Step 7: Craft a Conclusion

In this section, revisit the critical points of your piece, your findings in the article, and your critique. Also, write about the accuracy, validity, and relevance of the results of the article review. Present a way forward for future research in the field of study. Before submitting your article, keep these pointers in mind:

As you read the article, highlight the key points. This will help you pinpoint the article's main argument and the evidence that they used to support that argument.
While you write your review, use evidence from your sources to make a point. This is best done using direct quotations.
Select quotes and supporting evidence adequately and use direct quotations sparingly. Take time to analyze the article adequately.
Every time you reference a publication or use a direct quotation, use a parenthetical citation to avoid accidentally plagiarizing your article.
Re-read your piece a day after you finish writing it. This will help you to spot grammar mistakes and to notice any flaws in your organization.
Use a spell-checker and get a second opinion on your paper.

The Post-Writing Process: Proofread Your Work

Finally, when all of the parts of your article review are set and ready, you have one last thing to take care of — proofreading. Although students often neglect this step, proofreading is a vital part of the writing process and will help you polish your paper to ensure that there are no mistakes or inconsistencies.

To proofread your paper properly, start by reading it fully and checking the following points:

Punctuation
Other mistakes

Afterward, take a moment to check for any unnecessary information in your paper and, if found, consider removing it to streamline your content. Finally, double-check that you've covered at least 3-4 key points in your discussion.

And remember, if you ever need help with proofreading, rewriting your essay, or even want to buy essay , our friendly team is always here to assist you.

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How to write an article review, how to write an article review in apa format.

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How to write a superb literature review

Andy Tay is a freelance writer based in Singapore.

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Literature reviews are important resources for scientists. They provide historical context for a field while offering opinions on its future trajectory. Creating them can provide inspiration for one’s own research, as well as some practice in writing. But few scientists are trained in how to write a review — or in what constitutes an excellent one. Even picking the appropriate software to use can be an involved decision (see ‘Tools and techniques’). So Nature asked editors and working scientists with well-cited reviews for their tips.

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Correction 09 December 2020 : An earlier version of the tables in this article included some incorrect details about the programs Zotero, Endnote and Manubot. These have now been corrected.

Hsing, I.-M., Xu, Y. & Zhao, W. Electroanalysis 19 , 755–768 (2007).

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Ledesma, H. A. et al. Nature Nanotechnol. 14 , 645–657 (2019).

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Brahlek, M., Koirala, N., Bansal, N. & Oh, S. Solid State Commun. 215–216 , 54–62 (2015).

Choi, Y. & Lee, S. Y. Nature Rev. Chem . https://doi.org/10.1038/s41570-020-00221-w (2020).

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A journal article review is written for a reader who is knowledgeable in the discipline and is interested not just in the coverage and content of the article being reviewed, but also in your critical assessment of the ideas and argument that are being presented by the author.

Your review might be guided by the following questions:

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How to Write an Article Review: Template & Examples

An article review is an academic assignment that invites you to study a piece of academic research closely. Then, you should present its summary and critically evaluate it using the knowledge you’ve gained in class and during your independent study. If you get such a task at college or university, you shouldn’t confuse it with a response paper, which is a distinct assignment with other purposes (we’ll talk about it in detail below).

Our specialists will write a custom essay specially for you!

In this article, prepared by Custom-Writing experts, you’ll find:

the intricacies of article review writing;
the difference between an article review and similar assignments;
a step-by-step algorithm for review composition;
a couple of samples to guide you throughout the writing process.

So, if you wish to study our article review example and discover helpful writing tips, keep reading.

❓ What Is an Article Review?

✍️ Writing Steps

📑 Article Review Format

🔗 references.

An article review is an academic paper that summarizes and critically evaluates the information presented in your selected article.

This image shows what an article review is.

The first thing you should note when approaching the task of an article review is that not every article is suitable for this assignment. Let’s have a look at the variety of articles to understand what you can choose from.

Popular Vs. Scholarly Articles

In most cases, you’ll be required to review a scholarly, peer-reviewed article – one composed in compliance with rigorous academic standards. Yet, the Web is also full of popular articles that don’t present original scientific value and shouldn’t be selected for a review.

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Not sure how to distinguish these two types? Here is a comparative table to help you out.

Article Review vs. Response Paper

Now, let’s consider the difference between an article review and a response paper:

If you’re assigned to critique a scholarly article , you will need to compose an article review .
If your subject of analysis is a popular article , you can respond to it with a well-crafted response paper .

The reason for such distinctions is the quality and structure of these two article types. Peer-reviewed, scholarly articles have clear-cut quality criteria, allowing you to conduct and present a structured assessment of the assigned material. Popular magazines have loose or non-existent quality criteria and don’t offer an opportunity for structured evaluation. So, they are only fit for a subjective response, in which you can summarize your reactions and emotions related to the reading material.

All in all, you can structure your response assignments as outlined in the tips below.

✍️ How to Write an Article Review: Step by Step

Here is a tried and tested algorithm for article review writing from our experts. We’ll consider only the critical review variety of this academic assignment. So, let’s get down to the stages you need to cover to get a stellar review.

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Read the Article

As with any reviews, reports, and critiques, you must first familiarize yourself with the assigned material. It’s impossible to review something you haven’t read, so set some time for close, careful reading of the article to identify:

The author’s main points and message.
The arguments they use to prove their points.
The methodology they use to approach the subject.

In terms of research type , your article will usually belong to one of three types explained below.

Summarize the Article

Now that you’ve read the text and have a general impression of the content, it’s time to summarize it for your readers. Look into the article’s text closely to determine:

The thesis statement , or general message of the author.
Research question, purpose, and context of research.
Supporting points for the author’s assumptions and claims.
Major findings and supporting evidence.

As you study the article thoroughly, make notes on the margins or write these elements out on a sheet of paper. You can also apply a different technique: read the text section by section and formulate its gist in one phrase or sentence. Once you’re done, you’ll have a summary skeleton in front of you.

Evaluate the Article

The next step of review is content evaluation. Keep in mind that various research types will require a different set of review questions. Here is a complete list of evaluation points you can include.

Get an originally-written paper according to your instructions!

Write the Text

After completing the critical review stage, it’s time to compose your article review.

The format of this assignment is standard – you will have an introduction, a body, and a conclusion. The introduction should present your article and summarize its content. The body will contain a structured review according to all four dimensions covered in the previous section. The concluding part will typically recap all the main points you’ve identified during your assessment.

It is essential to note that an article review is, first of all, an academic assignment. Therefore, it should follow all rules and conventions of academic composition, such as:

No contractions . Don’t use short forms, such as “don’t,” “can’t,” “I’ll,” etc. in academic writing. You need to spell out all those words.
Formal language and style . Avoid conversational phrasing and words that you would naturally use in blog posts or informal communication. For example, don’t use words like “pretty,” “kind of,” and “like.”
Third-person narrative . Academic reviews should be written from the third-person point of view, avoiding statements like “I think,” “in my opinion,” and so on.
No conversational forms . You shouldn’t turn to your readers directly in the text by addressing them with the pronoun “you.” It’s vital to keep the narrative neutral and impersonal.
Proper abbreviation use . Consult the list of correct abbreviations , like “e.g.” or “i.e.,” for use in your academic writing. If you use informal abbreviations like “FYA” or “f.i.,” your professor will reduce the grade.
Complete sentences . Make sure your sentences contain the subject and the predicate; avoid shortened or sketch-form phrases suitable for a draft only.
No conjunctions at the beginning of a sentence . Remember the FANBOYS rule – don’t start a sentence with words like “and” or “but.” They often seem the right way to build a coherent narrative, but academic writing rules disfavor such usage.
No abbreviations or figures at the beginning of a sentence . Never start a sentence with a number — spell it out if you need to use it anyway. Besides, sentences should never begin with abbreviations like “e.g.”

Finally, a vital rule for an article review is properly formatting the citations. We’ll discuss the correct use of citation styles in the following section.

When composing an article review, keep these points in mind:

Start with a full reference to the reviewed article so the reader can locate it quickly.
Ensure correct formatting of in-text references.
Provide a complete list of used external sources on the last page of the review – your bibliographical entries .

You’ll need to understand the rules of your chosen citation style to meet all these requirements. Below, we’ll discuss the two most common referencing styles – APA and MLA.

Article Review in APA

When you need to compose an article review in the APA format , here is the general bibliographical entry format you should use for journal articles on your reference page:

Author’s last name, First initial. Middle initial. (Year of Publication). Name of the article. Name of the Journal, volume (number), pp. #-#. https://doi.org/xx.xxx/yyyy

Horigian, V. E., Schmidt, R. D., & Feaster, D. J. (2021). Loneliness, mental health, and substance use among US young adults during COVID-19. Journal of Psychoactive Drugs, 53 (1), pp. 1-9. https://doi.org/10.1080/02791072.2020.1836435

Your in-text citations should follow the author-date format like this:

If you paraphrase the source and mention the author in the text: According to Horigian et al. (2021), young adults experienced increased levels of loneliness, depression, and anxiety during the pandemic.
If you paraphrase the source and don’t mention the author in the text: Young adults experienced increased levels of loneliness, depression, and anxiety during the pandemic (Horigian et al., 2021).
If you quote the source: As Horigian et al. (2021) point out, there were “elevated levels of loneliness, depression, anxiety, alcohol use, and drug use among young adults during COVID-19” (p. 6).

Note that your in-text citations should include “et al.,” as in the examples above, if your article has 3 or more authors. If you have one or two authors, your in-text citations would look like this:

One author: “According to Smith (2020), depression is…” or “Depression is … (Smith, 2020).”
Two authors: “According to Smith and Brown (2020), anxiety means…” or “Anxiety means (Smith & Brown, 2020).”

Finally, in case you have to review a book or a website article, here are the general formats for citing these source types on your APA reference list.

Article Review in MLA

If your assignment requires MLA-format referencing, here’s the general format you should use for citing journal articles on your Works Cited page:

Author’s last name, First name. “Title of an Article.” Title of the Journal , vol. #, no. #, year, pp. #-#.

Horigian, Viviana E., et al. “Loneliness, Mental Health, and Substance Use Among US Young Adults During COVID-19.” Journal of Psychoactive Drugs , vol. 53, no. 1, 2021, pp. 1-9.

In-text citations in the MLA format follow the author-page citation format and look like this:

According to Horigian et al., young adults experienced increased levels of loneliness, depression, and anxiety during the pandemic (6).
Young adults experienced increased levels of loneliness, depression, and anxiety during the pandemic (Horigian et al. 6).

Like in APA, the abbreviation “et al.” is only needed in MLA if your article has 3 or more authors.

If you need to cite a book or a website page, here are the general MLA formats for these types of sources.

✅ Article Review Template

Here is a handy, universal article review template to help you move on with any review assignment. We’ve tried to make it as generic as possible to guide you in the academic process.

📝 Article Review Examples

The theory is good, but practice is even better. Thus, we’ve created three brief examples to show you how to write an article review. You can study the full-text samples by following the links.

📃 Men, Women, & Money

This article review examines a famous piece, “Men, Women & Money – How the Sexes Differ with Their Finances,” published by Amy Livingston in 2020. The author of this article claims that men generally spend more money than women. She makes this conclusion from a close analysis of gender-specific expenditures across five main categories: food, clothing, cars, entertainment, and general spending patterns. Livingston also looks at men’s approach to saving to argue that counter to the common perception of women’s light-hearted attitude to money, men are those who spend more on average.

📃 When and Why Nationalism Beats Globalism

This is a review of Jonathan Heidt’s 2016 article titled “When and Why Nationalism Beats Globalism,” written as an advocacy of right-wing populism rising in many Western states. The author illustrates the case with the election of Donald Trump as the US President and the rise of right-wing rhetoric in many Western countries. These examples show how nationalist sentiment represents a reaction to global immigration and a failure of globalization.

📃 Sleep Deprivation

This is a review of the American Heart Association’s article titled “The Dangers of Sleep Deprivation.” It discusses how the national organization concerned with the American population’s cardiovascular health links the lack of high-quality sleep to far-reaching health consequences. The organization’s experts reveal how a consistent lack of sleep leads to Alzheimer’s disease development, obesity, type 2 diabetes, etc.

✏️ Article Review FAQ

A high-quality article review should summarize the assigned article’s content and offer data-backed reactions and evaluations of its quality in terms of the article’s purpose, methodology, and data used to argue the main points. It should be detailed, comprehensive, objective, and evidence-based.

The purpose of writing a review is to allow students to reflect on research quality and showcase their critical thinking and evaluation skills. Students should exhibit their mastery of close reading of research publications and their unbiased assessment.

The content of your article review will be the same in any format, with the only difference in the assignment’s formatting before submission. Ensure you have a separate title page made according to APA standards and cite sources using the parenthetical author-date referencing format.

You need to take a closer look at various dimensions of an assigned article to compose a valuable review. Study the author’s object of analysis, the purpose of their research, the chosen method, data, and findings. Evaluate all these dimensions critically to see whether the author has achieved the initial goals. Finally, offer improvement recommendations to add a critique aspect to your paper.

Scientific Article Review: Duke University
Book and Article Reviews: William & Mary, Writing Resources Center
Sample Format for Reviewing a Journal Article: Boonshoft School of Medicine
Research Paper Review – Structure and Format Guidelines: New Jersey Institute of Technology
Article Review: University of Waterloo
Article Review: University of South Australia
How to Write a Journal Article Review: University of Newcastle Library Guides
Writing Help: The Article Review: Central Michigan University Libraries
Write a Critical Review of a Scientific Journal Article: McLaughlin Library
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Article Review

Article Review Writing: A Complete Step-by-Step Guide with Examples

What is an Article Review?

An article review is a critical evaluation and analysis of a piece of writing, typically an academic or journalistic article.

It goes beyond summarizing the content; it involves an in-depth examination of the author's ideas, arguments, and methodologies.

The goal is to provide a well-rounded understanding of the article's strengths, weaknesses, and overall contribution to the field.

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Types of Article Reviews

Article reviews come in various forms, each serving a distinct purpose in the realm of academic or professional discourse. Understanding these types is crucial for tailoring your approach.

Here are some common types of article reviews:

Journal Article Review

A journal article review involves a thorough evaluation of scholarly articles published in academic journals.

It requires summarizing the article's key points, methodology, and findings, emphasizing its contributions to the academic field.

Take a look at the following example to help you understand better.

Example of Journal Article Review

Research Article Review

A research article review focuses on scrutinizing articles with a primary emphasis on research.

This type of review involves evaluating the research design, methodology, results, and their broader implications.

Discussions on the interpretation of results, limitations, and the article's overall contributions are key.

Here is a sample for you to get an idea.

Example of Research Article Review

Science Article Review

A science article review specifically addresses articles within scientific disciplines. It includes summarizing scientific concepts, hypotheses, and experimental methods.

The type of review assesses the reliability of the experimental design, and evaluates the author's interpretation of findings.

Take a look at the following example.

Example of Science Article Review

Critical Review

A critical review involves a balanced critique of a given article. It encompasses providing a comprehensive summary, highlighting key points, and engaging in a critical analysis of strengths and weaknesses.

To get a clearer idea of a critical review, take a look at this example.

Critical Review Example

Article Review Format

When crafting an article review in either APA or MLA format, it's crucial to adhere to the specific guidelines for citing sources.

Below are the bibliographical entries for different types of sources in both APA and MLA styles:

How to Write an Article Review? 10 Easy Steps

Writing an effective article review involves a systematic approach. Follow this step-by-step process to ensure a comprehensive and well-structured analysis.

Step 1: Understand the Assignment

Before diving into the review, carefully read and understand the assignment guidelines.

Pay attention to specific requirements, such as word count, formatting style (APA, MLA), and the aspects your instructor wants you to focus on.

Step 2: Read the Article Thoroughly

Begin by thoroughly reading the article. Take notes on key points, arguments, and evidence presented by the author.

Understand the author's main thesis and the context in which the article was written.

Step 3: Create a Summary

Summarize the main points of the article. Highlight the author's key arguments and findings.

While writing the summary ensure that you capture the essential elements of the article to provide context for your analysis.

Step 4: Identify the Author's Thesis

In this step, pinpoint the author's main thesis or central argument. Understand the purpose of the article and how the author supports their position.

This will serve as a foundation for your critique.

Step 5: Evaluate the Author's Evidence and Methodology

Examine the evidence provided by the author to support their thesis. Assess the reliability and validity of the methodology used.

Consider the sources, data collection methods, and any potential biases.

Step 6: Analyze the Author's Writing Style

Evaluate the author's writing style and how effectively they communicate their ideas.

Consider the clarity of the language, the organization of the content, and the overall persuasiveness of the article.

Step 7: Consider the Article's Contribution

Reflect on the article's contribution to its field of study. Analyze how it fits into the existing literature, its significance, and any potential implications for future research or applications.

Step 8: Write the Introduction

Craft an introduction that includes the article's title, author, publication date, and a brief overview.

State the purpose of your review and your thesis—the main point you'll be analyzing in your review.

Step 9: Develop the Body of the Review

Organize your review by addressing specific aspects such as the author's thesis, methodology, writing style, and the article's contribution.

Use clear paragraphs to structure your analysis logically.

Step 10: Conclude with a Summary and Evaluation

Summarize your main points and restate your overall assessment of the article.

Offer insights into its strengths and weaknesses, and conclude with any recommendations for improvement or suggestions for further research.

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Article Review Outline

Creating a well-organized outline is an essential part of writing a coherent and insightful article review.

This outline given below will guide you through the key sections of your review, ensuring that your analysis is comprehensive and logically structured.

Refer to the following template to understand outlining the article review in detail.

Article Review Format Template

Article Review Examples

Examining article review examples can provide valuable insights into the structure, tone, and depth of analysis expected.

Below are sample article reviews, each illustrating a different approach and focus.

Example of Article Review

Sample of article review assignment pdf

Tips for Writing an Effective Article Review

Crafting an effective article review involves a combination of critical analysis, clarity, and structure.

Here are some valuable tips to guide you through the process:

Start with a Clear Introduction

Kick off your article review by introducing the article's main points and mentioning the publication date, which you can find on the re-title page. Outline the topics you'll cover in your review.

Concise Summary with Unanswered Questions

Provide a short summary of the article, emphasizing its main ideas. Highlight any lingering questions, known as "unanswered questions," that the article may have triggered. Use a basic article review template to help structure your thoughts.

Illustrate with Examples

Use examples from the article to illustrate your points. If there are tables or figures in the article, discuss them to make your review more concrete and easily understandable.

Organize Clearly with a Summary Section

Keep your review straightforward and well-organized. Begin with the start of the article, express your thoughts on what you liked or didn't like, and conclude with a summary section. This follows a basic plan for clarity.

Constructive Criticism

When providing criticism, be constructive. If there are elements you don't understand, frame them as "unanswered questions." This approach shows engagement and curiosity.

Smoothly Connect Your Ideas

Ensure your thoughts flow naturally throughout your review. Use simple words and sentences. If you have questions about the article, let them guide your review organically.

Revise and Check for Clarity

Before finishing, go through your review. Correct any mistakes and ensure it sounds clear. Check if you followed your plan, used simple words, and incorporated the keywords effectively. This makes your review better and more accessible for others.

In conclusion , writing an effective article review involves a thoughtful balance of summarizing key points, and addressing unanswered questions.

By following a simple and structured approach, you can create a review that not only analyzes the content but also adds value to the reader's understanding.

Remember to organize your thoughts logically, use clear language, and provide examples from the article to support your points.

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Article review writing format, steps, examples and illustration PDF Compiled by Mohammed Yismaw

2021, Article review writing format, steps, examples and illustration PDF Compiled by Mohammed Yismaw

The purpose of this document is to help students and researchers understand how a review of an academic journal is conducted and reported in different fields of study. Review articles in academic journals that analyze or discuss researches previously published by others, rather than reporting new research results or findings. Summaries and critiques are two ways to write a review of a scientific journal article. Both types of writing ask you first to read and understand an article from the primary literature about your topic. The summary involves briefly but accurately stating the key points of the article for a reader who has not read the original article. The critique begins by summarizing the article and then analyzes and evaluates the author’s research. Summaries and critiques help you learn to synthesize information from different sources and are usually limited to two pages maximum.

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Writing a Scientific Review Article: Comprehensive Insights for Beginners

Ayodeji amobonye.

1 Department of Biotechnology and Food Science, Faculty of Applied Sciences, Durban University of Technology, P.O. Box 1334, KwaZulu-Natal, Durban 4000, South Africa

2 Writing Centre, Durban University of Technology, P.O. Box 1334 KwaZulu-Natal, Durban 4000, South Africa

Japareng Lalung

3 School of Industrial Technology, Universiti Sains Malaysia, Gelugor 11800, Pulau Pinang, Malaysia

Santhosh Pillai

Associated data.

The data and materials that support the findings of this study are available from the corresponding author upon reasonable request.

Review articles present comprehensive overview of relevant literature on specific themes and synthesise the studies related to these themes, with the aim of strengthening the foundation of knowledge and facilitating theory development. The significance of review articles in science is immeasurable as both students and researchers rely on these articles as the starting point for their research. Interestingly, many postgraduate students are expected to write review articles for journal publications as a way of demonstrating their ability to contribute to new knowledge in their respective fields. However, there is no comprehensive instructional framework to guide them on how to analyse and synthesise the literature in their niches into publishable review articles. The dearth of ample guidance or explicit training results in students having to learn all by themselves, usually by trial and error, which often leads to high rejection rates from publishing houses. Therefore, this article seeks to identify these challenges from a beginner's perspective and strives to plug the identified gaps and discrepancies. Thus, the purpose of this paper is to serve as a systematic guide for emerging scientists and to summarise the most important information on how to write and structure a publishable review article.

1. Introduction

Early scientists, spanning from the Ancient Egyptian civilization to the Scientific Revolution of the 16 th /17 th century, based their research on intuitions, personal observations, and personal insights. Thus, less time was spent on background reading as there was not much literature to refer to. This is well illustrated in the case of Sir Isaac Newton's apple tree and the theory of gravity, as well as Gregor Mendel's pea plants and the theory of inheritance. However, with the astronomical expansion in scientific knowledge and the emergence of the information age in the last century, new ideas are now being built on previously published works, thus the periodic need to appraise the huge amount of already published literature [ 1 ]. According to Birkle et al. [ 2 ], the Web of Science—an authoritative database of research publications and citations—covered more than 80 million scholarly materials. Hence, a critical review of prior and relevant literature is indispensable for any research endeavour as it provides the necessary framework needed for synthesising new knowledge and for highlighting new insights and perspectives [ 3 ].

Review papers are generally considered secondary research publications that sum up already existing works on a particular research topic or question and relate them to the current status of the topic. This makes review articles distinctly different from scientific research papers. While the primary aim of the latter is to develop new arguments by reporting original research, the former is focused on summarising and synthesising previous ideas, studies, and arguments, without adding new experimental contributions. Review articles basically describe the content and quality of knowledge that are currently available, with a special focus on the significance of the previous works. To this end, a review article cannot simply reiterate a subject matter, but it must contribute to the field of knowledge by synthesising available materials and offering a scholarly critique of theory [ 4 ]. Typically, these articles critically analyse both quantitative and qualitative studies by scrutinising experimental results, the discussion of the experimental data, and in some instances, previous review articles to propose new working theories. Thus, a review article is more than a mere exhaustive compilation of all that has been published on a topic; it must be a balanced, informative, perspective, and unbiased compendium of previous studies which may also include contrasting findings, inconsistencies, and conventional and current views on the subject [ 5 ].

Hence, the essence of a review article is measured by what is achieved, what is discovered, and how information is communicated to the reader [ 6 ]. According to Steward [ 7 ], a good literature review should be analytical, critical, comprehensive, selective, relevant, synthetic, and fully referenced. On the other hand, a review article is considered to be inadequate if it is lacking in focus or outcome, overgeneralised, opinionated, unbalanced, and uncritical [ 7 ]. Most review papers fail to meet these standards and thus can be viewed as mere summaries of previous works in a particular field of study. In one of the few studies that assessed the quality of review articles, none of the 50 papers that were analysed met the predefined criteria for a good review [ 8 ]. However, beginners must also realise that there is no bad writing in the true sense; there is only writing in evolution and under refinement. Literally, every piece of writing can be improved upon, right from the first draft until the final published manuscript. Hence, a paper can only be referred to as bad and unfixable when the author is not open to corrections or when the writer gives up on it.

According to Peat et al. [ 9 ], “everything is easy when you know how,” a maxim which applies to scientific writing in general and review writing in particular. In this regard, the authors emphasized that the writer should be open to learning and should also follow established rules instead of following a blind trial-and-error approach. In contrast to the popular belief that review articles should only be written by experienced scientists and researchers, recent trends have shown that many early-career scientists, especially postgraduate students, are currently expected to write review articles during the course of their studies. However, these scholars have little or no access to formal training on how to analyse and synthesise the research literature in their respective fields [ 10 ]. Consequently, students seeking guidance on how to write or improve their literature reviews are less likely to find published works on the subject, particularly in the science fields. Although various publications have dealt with the challenges of searching for literature, or writing literature reviews for dissertation/thesis purposes, there is little or no information on how to write a comprehensive review article for publication. In addition to the paucity of published information to guide the potential author, the lack of understanding of what constitutes a review paper compounds their challenges. Thus, the purpose of this paper is to serve as a guide for writing review papers for journal publishing. This work draws on the experience of the authors to assist early-career scientists/researchers in the “hard skill” of authoring review articles. Even though there is no single path to writing scientifically, or to writing reviews in particular, this paper attempts to simplify the process by looking at this subject from a beginner's perspective. Hence, this paper highlights the differences between the types of review articles in the sciences while also explaining the needs and purpose of writing review articles. Furthermore, it presents details on how to search for the literature as well as how to structure the manuscript to produce logical and coherent outputs. It is hoped that this work will ease prospective scientific writers into the challenging but rewarding art of writing review articles.

2. Benefits of Review Articles to the Author

Analysing literature gives an overview of the “WHs”: WHat has been reported in a particular field or topic, WHo the key writers are, WHat are the prevailing theories and hypotheses, WHat questions are being asked (and answered), and WHat methods and methodologies are appropriate and useful [ 11 ]. For new or aspiring researchers in a particular field, it can be quite challenging to get a comprehensive overview of their respective fields, especially the historical trends and what has been studied previously. As such, the importance of review articles to knowledge appraisal and contribution cannot be overemphasised, which is reflected in the constant demand for such articles in the research community. However, it is also important for the author, especially the first-time author, to recognise the importance of his/her investing time and effort into writing a quality review article.

Generally, literature reviews are undertaken for many reasons, mainly for publication and for dissertation purposes. The major purpose of literature reviews is to provide direction and information for the improvement of scientific knowledge. They also form a significant component in the research process and in academic assessment [ 12 ]. There may be, however, a thin line between a dissertation literature review and a published review article, given that with some modifications, a literature review can be transformed into a legitimate and publishable scholarly document. According to Gülpınar and Güçlü [ 6 ], the basic motivation for writing a review article is to make a comprehensive synthesis of the most appropriate literature on a specific research inquiry or topic. Thus, conducting a literature review assists in demonstrating the author's knowledge about a particular field of study, which may include but not be limited to its history, theories, key variables, vocabulary, phenomena, and methodologies [ 10 ]. Furthermore, publishing reviews is beneficial as it permits the researchers to examine different questions and, as a result, enhances the depth and diversity of their scientific reasoning [ 1 ]. In addition, writing review articles allows researchers to share insights with the scientific community while identifying knowledge gaps to be addressed in future research. The review writing process can also be a useful tool in training early-career scientists in leadership, coordination, project management, and other important soft skills necessary for success in the research world [ 13 ]. Another important reason for authoring reviews is that such publications have been observed to be remarkably influential, extending the reach of an author in multiple folds of what can be achieved by primary research papers [ 1 ]. The trend in science is for authors to receive more citations from their review articles than from their original research articles. According to Miranda and Garcia-Carpintero [ 14 ], review articles are, on average, three times more frequently cited than original research articles; they also asserted that a 20% increase in review authorship could result in a 40–80% increase in citations of the author. As a result, writing reviews can significantly impact a researcher's citation output and serve as a valuable channel to reach a wider scientific audience. In addition, the references cited in a review article also provide the reader with an opportunity to dig deeper into the topic of interest. Thus, review articles can serve as a valuable repository for consultation, increasing the visibility of the authors and resulting in more citations.

3. Types of Review Articles

The first step in writing a good literature review is to decide on the particular type of review to be written; hence, it is important to distinguish and understand the various types of review articles. Although scientific review articles have been classified according to various schemes, however, they are broadly categorised into narrative reviews, systematic reviews, and meta-analyses [ 15 ]. It was observed that more authors—as well as publishers—were leaning towards systematic reviews and meta-analysis while downplaying narrative reviews; however, the three serve different aims and should all be considered equally important in science [ 1 ]. Bibliometric reviews and patent reviews, which are closely related to meta-analysis, have also gained significant attention recently. However, from another angle, a review could also be of two types. In the first class, authors could deal with a widely studied topic where there is already an accumulated body of knowledge that requires analysis and synthesis [ 3 ]. At the other end of the spectrum, the authors may have to address an emerging issue that would benefit from exposure to potential theoretical foundations; hence, their contribution would arise from the fresh theoretical foundations proposed in developing a conceptual model [ 3 ].

3.1. Narrative Reviews

Narrative reviewers are mainly focused on providing clarification and critical analysis on a particular topic or body of literature through interpretative synthesis, creativity, and expert judgement. According to Green et al. [ 16 ], a narrative review can be in the form of editorials, commentaries, and narrative overviews. However, editorials and commentaries are usually expert opinions; hence, a beginner is more likely to write a narrative overview, which is more general and is also referred to as an unsystematic narrative review. Similarly, the literature review section of most dissertations and empirical papers is typically narrative in nature. Typically, narrative reviews combine results from studies that may have different methodologies to address different questions or to formulate a broad theoretical formulation [ 1 ]. They are largely integrative as strong focus is placed on the assimilation and synthesis of various aspects in the review, which may involve comparing and contrasting research findings or deriving structured implications [ 17 ]. In addition, they are also qualitative studies because they do not follow strict selection processes; hence, choosing publications is relatively more subjective and unsystematic [ 18 ]. However, despite their popularity, there are concerns about their inherent subjectivity. In many instances, when the supporting data for narrative reviews are examined more closely, the evaluations provided by the author(s) become quite questionable [ 19 ]. Nevertheless, if the goal of the author is to formulate a new theory that connects diverse strands of research, a narrative method is most appropriate.

3.2. Systematic Reviews

In contrast to narrative reviews, which are generally descriptive, systematic reviews employ a systematic approach to summarise evidence on research questions. Hence, systematic reviews make use of precise and rigorous criteria to identify, evaluate, and subsequently synthesise all relevant literature on a particular topic [ 12 , 20 ]. As a result, systematic reviews are more likely to inspire research ideas by identifying knowledge gaps or inconsistencies, thus helping the researcher to clearly define the research hypotheses or questions [ 21 ]. Furthermore, systematic reviews may serve as independent research projects in their own right, as they follow a defined methodology to search and combine reliable results to synthesise a new database that can be used for a variety of purposes [ 22 ]. Typically, the peculiarities of the individual reviewer, different search engines, and information databases used all ensure that no two searches will yield the same systematic results even if the searches are conducted simultaneously and under identical criteria [ 11 ]. Hence, attempts are made at standardising the exercise via specific methods that would limit bias and chance effects, prevent duplications, and provide more accurate results upon which conclusions and decisions can be made.

The most established of these methods is the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines which objectively defined statements, guidelines, reporting checklists, and flowcharts for undertaking systematic reviews as well as meta-analysis [ 23 ]. Though mainly designed for research in medical sciences, the PRISMA approach has gained wide acceptance in other fields of science and is based on eight fundamental propositions. These include the explicit definition of the review question, an unambiguous outline of the study protocol, an objective and exhaustive systematic review of reputable literature, and an unambiguous identification of included literature based on defined selection criteria [ 24 ]. Other considerations include an unbiased appraisal of the quality of the selected studies (literature), organic synthesis of the evidence of the study, preparation of the manuscript based on the reporting guidelines, and periodic update of the review as new data emerge [ 24 ]. Other methods such as PRISMA-P (Preferred Reporting Items for Systematic review and Meta-Analysis Protocols), MOOSE (Meta-analysis Of Observational Studies in Epidemiology), and ROSES (Reporting Standards for Systematic Evidence Syntheses) have since been developed for systematic reviews (and meta-analysis), with most of them being derived from PRISMA.

Consequently, systematic reviews—unlike narrative reviews—must contain a methodology section which in addition to all that was highlighted above must fully describe the precise criteria used in formulating the research question and setting the inclusion or exclusion criteria used in selecting/accessing the literature. Similarly, the criteria for evaluating the quality of the literature included in the review as well as for analysing, synthesising, and disseminating the findings must be fully described in the methodology section.

3.3. Meta-Analysis

Meta-analyses are considered as more specialised forms of systematic reviews. Generally, they combine the results of many studies that use similar or closely related methods to address the same question or share a common quantitative evaluation method [ 25 ]. However, meta-analyses are also a step higher than other systematic reviews as they are focused on numerical data and involve the use of statistics in evaluating different studies and synthesising new knowledge. The major advantage of this type of review is the increased statistical power leading to more reliable results for inferring modest associations and a more comprehensive understanding of the true impact of a research study [ 26 ]. Unlike in traditional systematic reviews, research topics covered in meta-analyses must be mature enough to allow the inclusion of sufficient homogeneous empirical research in terms of subjects, interventions, and outcomes [ 27 , 28 ].

Being an advanced form of systematic review, meta-analyses must also have a distinct methodology section; hence, the standard procedures involved in the traditional systematic review (especially PRISMA) also apply in meta-analyses [ 23 ]. In addition to the common steps in formulating systematic reviews, meta-analyses are required to describe how nested and missing data are handled, the effect observed in each study, the confidence interval associated with each synthesised effect, and any potential for bias presented within the sample(s) [ 17 ]. According to Paul and Barari [ 28 ], a meta-analysis must also detail the final sample, the meta-analytic model, and the overall analysis, moderator analysis, and software employed. While the overall analysis involves the statistical characterization of the relationships between variables in the meta-analytic framework and their significance, the moderator analysis defines the different variables that may affect variations in the original studies [ 28 , 29 ]. It must also be noted that the accuracy and reliability of meta-analyses have both been significantly enhanced by the incorporation of statistical approaches such as Bayesian analysis [ 30 ], network analysis [ 31 ], and more recently, machine learning [ 32 ].

3.4. Bibliometric Review

A bibliometric review, commonly referred to as bibliometric analysis, is a systematic evaluation of published works within a specific field or discipline [ 33 ]. This bibliometric methodology involves the use of quantitative methods to analyse bibliometric data such as the characteristics and numbers of publications, units of citations, authorship, co-authorship, and journal impact factors [ 34 ]. Academics use bibliometric analysis with different objectives in mind, which includes uncovering emerging trends in article and journal performance, elaborating collaboration patterns and research constituents, evaluating the impact and influence of particular authors, publications, or research groups, and highlighting the intellectual framework of a certain field [ 35 ]. It is also used to inform policy and decision-making. Similarly to meta-analysis, bibliometric reviews rely upon quantitative techniques, thus avoiding the interpretation bias that could arise from the qualitative techniques of other types of reviews [ 36 ]. However, while bibliometric analysis synthesises the bibliometric and intellectual structure of a field by examining the social and structural linkages between various research parts, meta-analysis focuses on summarising empirical evidence by probing the direction and strength of effects and relationships among variables, especially in open research questions [ 37 , 38 ]. However, similarly to systematic review and meta-analysis, a bibliometric review also requires a well-detailed methodology section. The amount of data to be analysed in bibliometric analysis is quite massive, running to hundreds and tens of thousands in some cases. Although the data are objective in nature (e.g., number of citations and publications and occurrences of keywords and topics), the interpretation is usually carried out through both objective (e.g., performance analysis) and subjective (e.g., thematic analysis) evaluations [ 35 ]. However, the invention and availability of bibliometric software such as BibExcel, Gephi, Leximancer, and VOSviewer and scientific databases such as Dimensions, Web of Science, and Scopus have made this type of analysis more feasible.

3.5. Patent Review

Patent reviews provide a comprehensive analysis and critique of a specific patent or a group of related patents, thus presenting a concise understanding of the technology or innovation that is covered by the patent [ 39 ]. This type of article is useful for researchers as it also enhances their understanding of the legal, technical, and commercial aspects of an intellectual property/innovation; in addition, it is also important for stakeholders outside the research community including IP (intellectual property) specialists, legal professionals, and technology-transfer officers [ 40 ]. Typically, patent reviews encompass the scope, background, claims, legal implications, technical specifications, and potential commercial applications of the patent(s). The article may also include a discussion of the patent's strengths and weaknesses, as well as its potential impact on the industry or field in which it operates. Most times, reviews are time specified, they may be regionalised, and the data are usually retrieved via patent searches on databases such as that of the European Patent Office ( https://www.epo.org/searching.html ), United States Patent and Trademark Office ( https://patft.uspto.gov/ ), the World Intellectual Property Organization's PATENTSCOPE ( https://patentscope.wipo.int/search/en/structuredSearch.jsf ), Google Patent ( https://www.google.com/?tbm=pts ), and China National Intellectual Property Administration ( https://pss-system.cponline.cnipa.gov.cn/conventionalSearch ). According to Cerimi et al. [ 41 ], the retrieved data and analysed may include the patent number, patent status, filing date, application date, grant dates, inventor, assignee, and pending applications. While data analysis is usually carried out by general data software such as Microsoft Excel, an intelligence software solely dedicated to patent research and analysis, Orbit Intelligence has been found to be more efficient [ 39 ]. It is also mandatory to include a methodology section in a patent review, and this should be explicit, thorough, and precise to allow a clear understanding of how the analysis was carried out and how the conclusions were arrived at.

4. Searching Literature

One of the most challenging tasks in writing a review article on a subject is the search for relevant literature to populate the manuscript as the author is required to garner information from an endless number of sources. This is even more challenging as research outputs have been increasing astronomically, especially in the last decade, with thousands of new articles published annually in various fields. It is therefore imperative that the author must not only be aware of the overall trajectory in a field of investigation but must also be cognizant of recent studies so as not to publish outdated research or review articles. Basically, the search for the literature involves a coherent conceptual structuring of the topic itself and a thorough collation of evidence under the common themes which might reflect the histories, conflicts, standoffs, revolutions, and/or evolutions in the field [ 7 ]. To start the search process, the author must carefully identify and select broad keywords relevant to the subject; subsequently, the keywords should be developed to refine the search into specific subheadings that would facilitate the structure of the review.

Two main tactics have been identified for searching the literature, namely, systematic and snowballing [ 42 ]. The systematic approach involves searching literature with specific keywords (for example, cancer, antioxidant, and nanoparticles), which leads to an almost unmanageable and overwhelming list of possible sources [ 43 ]. The snowballing approach, however, involves the identification of a particular publication, followed by the compilation of a bibliography of articles based on the reference list of the identified publication [ 44 ]. Many times, it might be necessary to combine both approaches, but irrespective, the author must keep an accurate track and record of papers cited in the search. A simple and efficient strategy for populating the bibliography of review articles is to go through the abstract (and sometimes the conclusion) of a paper; if the abstract is related to the topic of discourse, the author might go ahead and read the entire article; otherwise, he/she is advised to move on [ 45 ]. Winchester and Salji [ 5 ] noted that to learn the background of the subject/topic to be reviewed, starting literature searches with academic textbooks or published review articles is imperative, especially for beginners. Furthermore, it would also assist in compiling the list of keywords, identifying areas of further exploration, and providing a glimpse of the current state of the research. However, past reviews ideally are not to serve as the foundation of a new review as they are written from someone else's viewpoint, which might have been tainted with some bias. Fortunately, the accessibility and search for the literature have been made relatively easier than they were a few decades ago as the current information age has placed an enormous volume of knowledge right at our fingertips [ 46 ]. Nevertheless, when gathering the literature from the Internet, authors should exercise utmost caution as much of the information may not be verified or peer-reviewed and thus may be unregulated and unreliable. For instance, Wikipedia, despite being a large repository of information with more than 6.7 million articles in the English language alone, is considered unreliable for scientific literature reviews, due to its openness to public editing [ 47 ]. However, in addition to peer-reviewed journal publications—which are most ideal—reviews can also be drawn from a wide range of other sources such as technical documents, in-house reports, conference abstracts, and conference proceedings. Similarly, “Google Scholar”—as against “Google” and other general search engines—is more appropriate as its searches are restricted to only academic articles produced by scholarly societies or/and publishers [ 48 ]. Furthermore, the various electronic databases, such as ScienceDirect, Web of Science, PubMed, and MEDLINE, many of which focus on specific fields of research, are also ideal options [ 49 ]. Advancement in computer indexing has remarkably expanded the ease and ability to search large databases for every potentially relevant article. In addition to searching by topic, literature search can be modified by time; however, there must be a balance between old papers and recent ones. The general consensus in science is that publications less than five years old are considered recent.

It is important, especially in systematic reviews and meta-analyses, that the specific method of running the computer searches be properly documented as there is the need to include this in the method (methodology) section of such papers. Typically, the method details the keywords, databases explored, search terms used, and the inclusion/exclusion criteria applied in the selection of data and any other specific decision/criteria. All of these will ensure the reproducibility and thoroughness of the search and the selection procedure. However, Randolph [ 10 ] noted that Internet searches might not give the exhaustive list of articles needed for a review article; hence, it is advised that authors search through the reference lists of articles that were obtained initially from the Internet search. After determining the relevant articles from the list, the author should read through the references of these articles and repeat the cycle until saturation is reached [ 10 ]. After populating the articles needed for the literature review, the next step is to analyse them individually and in their whole entirety. A systematic approach to this is to identify the key information within the papers, examine them in depth, and synthesise original perspectives by integrating the information and making inferences based on the findings. In this regard, it is imperative to link one source to the other in a logical manner, for instance, taking note of studies with similar methodologies, papers that agree, or results that are contradictory [ 42 ].

5. Structuring the Review Article

The title and abstract are the main selling points of a review article, as most readers will only peruse these two elements and usually go on to read the full paper if they are drawn in by either or both of the two. Tullu [ 50 ] recommends that the title of a scientific paper “should be descriptive, direct, accurate, appropriate, interesting, concise, precise, unique, and not be misleading.” In addition to providing “just enough details” to entice the reader, words in the titles are also used by electronic databases, journal websites, and search engines to index and retrieve a particular paper during a search [ 51 ]. Titles are of different types and must be chosen according to the topic under review. They are generally classified as descriptive, declarative, or interrogative and can also be grouped into compound, nominal, or full-sentence titles [ 50 ]. The subject of these categorisations has been extensively discussed in many articles; however, the reader must also be aware of the compound titles, which usually contain a main title and a subtitle. Typically, subtitles provide additional context—to the main title—and they may specify the geographic scope of the research, research methodology, or sample size [ 52 ].

Just like primary research articles, there are many debates about the optimum length of a review article's title. However, the general consensus is to keep the title as brief as possible while not being too general. A title length between 10 and 15 words is recommended, since longer titles can be more challenging to comprehend. Paiva et al. [ 53 ] observed that articles which contain 95 characters or less get more views and citations. However, emphasis must be placed on conciseness as the audience will be more satisfied if they can understand what exactly the review has contributed to the field, rather than just a hint about the general topic area. Authors should also endeavour to stick to the journal's specific requirements, especially regarding the length of the title and what they should or should not contain [ 9 ]. Thus, avoidance of filler words such as “a review on/of,” “an observation of,” or “a study of” is a very simple way to limit title length. In addition, abbreviations or acronyms should be avoided in the title, except the standard or commonly interpreted ones such as AIDS, DNA, HIV, and RNA. In summary, to write an effective title, the authors should consider the following points. What is the paper about? What was the methodology used? What were the highlights and major conclusions? Subsequently, the author should list all the keywords from these answers, construct a sentence from these keywords, and finally delete all redundant words from the sentence title. It is also possible to gain some ideas by scanning indices and article titles in major journals in the field. It is important to emphasise that a title is not chosen and set in stone, and the title is most likely to be continually revised and adjusted until the end of the writing process.

5.2. Abstract

The abstract, also referred to as the synopsis, is a summary of the full research paper; it is typically independent and can stand alone. For most readers, a publication does not exist beyond the abstract, partly because abstracts are often the only section of a paper that is made available to the readers at no cost, whereas the full paper may attract a payment or subscription [ 54 ]. Thus, the abstract is supposed to set the tone for the few readers who wish to read the rest of the paper. It has also been noted that the abstract gives the first impression of a research work to journal editors, conference scientific committees, or referees, who might outright reject the paper if the abstract is poorly written or inadequate [ 50 ]. Hence, it is imperative that the abstract succinctly represents the entire paper and projects it positively. Just like the title, abstracts have to be balanced, comprehensive, concise, functional, independent, precise, scholarly, and unbiased and not be misleading [ 55 ]. Basically, the abstract should be formulated using keywords from all the sections of the main manuscript. Thus, it is pertinent that the abstract conveys the focus, key message, rationale, and novelty of the paper without any compromise or exaggeration. Furthermore, the abstract must be consistent with the rest of the paper; as basic as this instruction might sound, it is not to be taken for granted. For example, a study by Vrijhoef and Steuten [ 56 ] revealed that 18–68% of 264 abstracts from some scientific journals contained information that was inconsistent with the main body of the publications.

Abstracts can either be structured or unstructured; in addition, they can further be classified as either descriptive or informative. Unstructured abstracts, which are used by many scientific journals, are free flowing with no predefined subheadings, while structured abstracts have specific subheadings/subsections under which the abstract needs to be composed. Structured abstracts have been noted to be more informative and are usually divided into subsections which include the study background/introduction, objectives, methodology design, results, and conclusions [ 57 ]. No matter the style chosen, the author must carefully conform to the instructions provided by the potential journal of submission, which may include but are not limited to the format, font size/style, word limit, and subheadings [ 58 ]. The word limit for abstracts in most scientific journals is typically between 150 and 300 words. It is also a general rule that abstracts do not contain any references whatsoever.

Typically, an abstract should be written in the active voice, and there is no such thing as a perfect abstract as it could always be improved on. It is advised that the author first makes an initial draft which would contain all the essential parts of the paper, which could then be polished subsequently. The draft should begin with a brief background which would lead to the research questions. It might also include a general overview of the methodology used (if applicable) and importantly, the major results/observations/highlights of the review paper. The abstract should end with one or few sentences about any implications, perspectives, or future research that may be developed from the review exercise. Finally, the authors should eliminate redundant words and edit the abstract to the correct word count permitted by the journal [ 59 ]. It is always beneficial to read previous abstracts published in the intended journal, related topics/subjects from other journals, and other reputable sources. Furthermore, the author should endeavour to get feedback on the abstract especially from peers and co-authors. As the abstract is the face of the whole paper, it is best that it is the last section to be finalised, as by this time, the author would have developed a clearer understanding of the findings and conclusions of the entire paper.

5.3. Graphical Abstracts

Since the mid-2000s, an increasing number of journals now require authors to provide a graphical abstract (GA) in addition to the traditional written abstract, to increase the accessibility of scientific publications to readers [ 60 ]. A study showed that publications with GA performed better than those without it, when the abstract views, total citations, and downloads were compared [ 61 ]. However, the GA should provide “a single, concise pictorial, and visual summary of the main findings of an article” [ 62 ]. Although they are meant to be a stand-alone summary of the whole paper, it has been noted that they are not so easily comprehensible without having read through the traditionally written abstract [ 63 ]. It is important to note that, like traditional abstracts, many reputable journals require GAs to adhere to certain specifications such as colour, dimension, quality, file size, and file format (usually JPEG/JPG, PDF, PNG, or TIFF). In addition, it is imperative to use engaging and accurate figures, all of which must be synthesised in order to accurately reflect the key message of the paper. Currently, there are various online or downloadable graphical tools that can be used for creating GAs, such as Microsoft Paint or PowerPoint, Mindthegraph, ChemDraw, CorelDraw, and BioRender.

5.4. Keywords

As a standard practice, journals require authors to select 4–8 keywords (or phrases), which are typically listed below the abstract. A good set of keywords will enable indexers and search engines to find relevant papers more easily and can be considered as a very concise abstract [ 64 ]. According to Dewan and Gupta [ 51 ], the selection of appropriate keywords will significantly enhance the retrieval, accession, and consequently, the citation of the review paper. Ideally, keywords can be variants of the terms/phrases used in the title, the abstract, and the main text, but they should ideally not be the exact words in the main title. Choosing the most appropriate keywords for a review article involves listing down the key terms and phrases in the article, including abbreviations. Subsequently, a quick review of the glossary/vocabulary/term list or indexing standard in the specific discipline will assist in selecting the best and most precise keywords that match those used in the databases from the list drawn. In addition, the keywords should not be broad or general terms (e.g., DNA, biology, and enzymes) but must be specific to the field or subfield of study as well as to the particular paper [ 65 ].

5.5. Introduction

The introduction of an article is the first major section of the manuscript, and it presents basic information to the reader without compelling them to study past publications. In addition, the introduction directs the reader to the main arguments and points developed in the main body of the article while clarifying the current state of knowledge in that particular area of research [ 12 ]. The introduction part of a review article is usually sectionalised into background information, a description of the main topic and finally a statement of the main purpose of the review [ 66 ]. Authors may begin the introduction with brief general statements—which provide background knowledge on the subject matter—that lead to more specific ones [ 67 ]. It is at this point that the reader's attention must be caught as the background knowledge must highlight the importance and justification for the subject being discussed, while also identifying the major problem to be addressed [ 68 ]. In addition, the background should be broad enough to attract even nonspecialists in the field to maximise the impact and widen the reach of the article. All of these should be done in the light of current literature; however, old references may also be used for historical purposes. A very important aspect of the introduction is clearly stating and establishing the research problem(s) and how a review of the particular topic contributes to those problem(s). Thus, the research gap which the paper intends to fill, the limitations of previous works and past reviews, if available, and the new knowledge to be contributed must all be highlighted. Inadequate information and the inability to clarify the problem will keep readers (who have the desire to obtain new information) from reading beyond the introduction [ 69 ]. It is also pertinent that the author establishes the purpose of reviewing the literature and defines the scope as well as the major synthesised point of view. Furthermore, a brief insight into the criteria used to select, evaluate, and analyse the literature, as well as the outline or sequence of the review, should be provided in the introduction. Subsequently, the specific objectives of the review article must be presented. The last part of the “introduction” section should focus on the solution, the way forward, the recommendations, and the further areas of research as deduced from the whole review process. According to DeMaria [ 70 ], clearly expressed or recommended solutions to an explicitly revealed problem are very important for the wholesomeness of the “introduction” section. It is believed that following these steps will give readers the opportunity to track the problems and the corresponding solution from their own perspective in the light of current literature. As against some suggestions that the introduction should be written only in present tenses, it is also believed that it could be done with other tenses in addition to the present tense. In this regard, general facts should be written in the present tense, specific research/work should be in the past tense, while the concluding statement should be in the past perfect or simple past. Furthermore, many of the abbreviations to be used in the rest of the manuscript and their explanations should be defined in this section.

5.6. Methodology

Writing a review article is equivalent to conducting a research study, with the information gathered by the author (reviewer) representing the data. Like all major studies, it involves conceptualisation, planning, implementation, and dissemination [ 71 ], all of which may be detailed in a methodology section, if necessary. Hence, the methodological section of a review paper (which can also be referred to as the review protocol) details how the relevant literature was selected and how it was analysed as well as summarised. The selection details may include, but are not limited to, the database consulted and the specific search terms used together with the inclusion/exclusion criteria. As earlier highlighted in Section 3 , a description of the methodology is required for all types of reviews except for narrative reviews. This is partly because unlike narrative reviews, all other review articles follow systematic approaches which must ensure significant reproducibility [ 72 ]. Therefore, where necessary, the methods of data extraction from the literature and data synthesis must also be highlighted as well. In some cases, it is important to show how data were combined by highlighting the statistical methods used, measures of effect, and tests performed, as well as demonstrating heterogeneity and publication bias [ 73 ].

The methodology should also detail the major databases consulted during the literature search, e.g., Dimensions, ScienceDirect, Web of Science, MEDLINE, and PubMed. For meta-analysis, it is imperative to highlight the software and/or package used, which could include Comprehensive Meta-Analysis, OpenMEE, Review Manager (RevMan), Stata, SAS, and R Studio. It is also necessary to state the mathematical methods used for the analysis; examples of these include the Bayesian analysis, the Mantel–Haenszel method, and the inverse variance method. The methodology should also state the number of authors that carried out the initial review stage of the study, as it has been recommended that at least two reviews should be done blindly and in parallel, especially when it comes to the acquisition and synthesis of data [ 74 ]. Finally, the quality and validity assessment of the publication used in the review must be stated and well clarified [ 73 ].

5.7. Main Body of the Review

Ideally, the main body of a publishable review should answer these questions: What is new (contribution)? Why so (logic)? So what (impact)? How well it is done (thoroughness)? The flow of the main body of a review article must be well organised to adequately maintain the attention of the readers as well as guide them through the section. It is recommended that the author should consider drawing a conceptual scheme of the main body first, using methods such as mind-mapping. This will help create a logical flow of thought and presentation, while also linking the various sections of the manuscript together. According to Moreira [ 75 ], “reports do not simply yield their findings, rather reviewers make them yield,” and thus, it is the author's responsibility to transform “resistant” texts into “docile” texts. Hence, after the search for the literature, the essential themes and key concepts of the review paper must be identified and synthesised together. This synthesis primarily involves creating hypotheses about the relationships between the concepts with the aim of increasing the understanding of the topic being reviewed. The important information from the various sources should not only be summarised, but the significance of studies must be related back to the initial question(s) posed by the review article. Furthermore, MacLure [ 76 ] stated that data are not just to be plainly “extracted intact” and “used exactly as extracted,” but must be modified, reconfigured, transformed, transposed, converted, tabulated, graphed, or manipulated to enable synthesis, combination, and comparison. Therefore, different pieces of information must be extracted from the reports in which they were previously deposited and then refined into the body of the new article [ 75 ]. To this end, adequate comparison and combination might require that “qualitative data be quantified” or/and “quantitative data may be qualitized” [ 77 ]. In order to accomplish all of these goals, the author may have to transform, paraphrase, generalize, specify, and reorder the text [ 78 ]. For comprehensiveness, the body paragraphs should be arranged in a similar order as it was initially stated in the abstract or/and introduction. Thus, the main body could be divided into thematic areas, each of which could be independently comprehensive and treated as a mini review. Similarly, the sections can also be arranged chronologically depending on the focus of the review. Furthermore, the abstractions should proceed from a wider general view of the literature being reviewed and then be narrowed down to the specifics. In the process, deep insights should also be provided between the topic of the review and the wider subject area, e.g., fungal enzymes and enzymes in general. The abstractions must also be discussed in more detail by presenting more specific information from the identified sources (with proper citations of course!). For example, it is important to identify and highlight contrary findings and rival interpretations as well as to point out areas of agreement or debate among different bodies of literature. Often, there are previous reviews on the same topic/concept; however, this does not prevent a new author from writing one on the same topic, especially if the previous reviews were written many years ago. However, it is important that the body of the new manuscript be written from a new angle that was not adequately covered in the past reviews and should also incorporate new studies that have accumulated since the last review(s). In addition, the new review might also highlight the approaches, limitations, and conclusions of the past studies. But the authors must not be excessively critical of the past reviews as this is regarded by many authors as a sign of poor professionalism [ 3 , 79 ]. Daft [ 79 ] emphasized that it is more important for a reviewer to state how their research builds on previous work instead of outright claiming that previous works are incompetent and inadequate. However, if a series of related papers on one topic have a common error or research flaw that needs rectification, the reviewer must point this out with the aim of moving the field forward [ 3 ]. Like every other scientific paper, the main body of a review article also needs to be consistent in style, for example, in the choice of passive vs. active voice and present vs. past tense. It is also important to note that tables and figures can serve as a powerful tool for highlighting key points in the body of the review, and they are now considered core elements of reviews. For more guidance and insights into what should make up the contents of a good review article, readers are also advised to get familiarised with the Boote and Beile [ 80 ] literature review scoring rubric as well as the review article checklist of Short [ 81 ].

5.8. Tables and Figures

An ideal review article should be logically structured and efficiently utilise illustrations, in the form of tables and figures, to convey the key findings and relationships in the study. According to Tay [ 13 ], illustrations often take a secondary role in review papers when compared to primary research papers which are focused on illustrations. However, illustrations are very important in review articles as they can serve as succinct means of communicating major findings and insights. Franzblau and Chung [ 82 ] pointed out that illustrations serve three major purposes in a scientific article: they simplify complex data and relationships for better understanding, they minimise reading time by summarising and bringing to focus on the key findings (or trends), and last, they help to reduce the overall word count. Hence, inserting and constructing illustrations in a review article is as meticulous as it is important. However, important decisions should be made on whether the charts, figures, or tables to be potentially inserted in the manuscript are indeed needed and how best to design them [ 83 ]. Illustrations should enhance the text while providing necessary information; thus, the information described in illustrations should not contradict that in the main text and should also not be a repetition of texts [ 84 ]. Furthermore, illustrations must be autonomous, meaning they ought to be intelligible without having to read the text portion of the manuscript; thus, the reader does not have to flip back and forth between the illustration and the main text in order to understand it [ 85 ]. It should be noted that tables or figures that directly reiterate the main text or contain extraneous information will only make a mess of the manuscript and discourage readers [ 86 ].

Kotz and Cals [ 87 ] recommend that the layout of tables and figures should be carefully designed in a clear manner with suitable layouts, which will allow them to be referred to logically and chronologically in the text. In addition, illustrations should only contain simple text, as lengthy details would contradict their initial objective, which was to provide simple examples or an overview. Furthermore, the use of abbreviations in illustrations, especially tables, should be avoided if possible. If not, the abbreviations should be defined explicitly in the footnotes or legends of the illustration [ 88 ]. Similarly, numerical values in tables and graphs should also be correctly approximated [ 84 ]. It is recommended that the number of tables and figures in the manuscript should not exceed the target journal's specification. According to Saver [ 89 ], they ideally should not account for more than one-third of the manuscript. Finally, the author(s) must seek permission and give credits for using an already published illustration when necessary. However, none of these are needed if the graphic is originally created by the author, but if it is a reproduced or an adapted illustration, the author must obtain permission from the copyright owner and include the necessary credit. One of the very important tools for designing illustrations is Creative Commons, a platform that provides a wide range of creative works which are available to the public for use and modification.

5.9. Conclusion/Future Perspectives

It has been observed that many reviews end abruptly with a short conclusion; however, a lot more can be included in this section in addition to what has been said in the major sections of the paper. Basically, the conclusion section of a review article should provide a summary of key findings from the main body of the manuscript. In this section, the author needs to revisit the critical points of the paper as well as highlight the accuracy, validity, and relevance of the inferences drawn in the article review. A good conclusion should highlight the relationship between the major points and the author's hypothesis as well as the relationship between the hypothesis and the broader discussion to demonstrate the significance of the review article in a larger context. In addition to giving a concise summary of the important findings that describe current knowledge, the conclusion must also offer a rationale for conducting future research [ 12 ]. Knowledge gaps should be identified, and themes should be logically developed in order to construct conceptual frameworks as well as present a way forward for future research in the field of study [ 11 ].

Furthermore, the author may have to justify the propositions made earlier in the manuscript, demonstrate how the paper extends past research works, and also suggest ways that the expounded theories can be empirically examined [ 3 ]. Unlike experimental studies which can only draw either a positive conclusion or ambiguous failure to reject the null hypothesis, four possible conclusions can be drawn from review articles [ 1 ]. First, the theory/hypothesis propounded may be correct after being proven from current evidence; second, the hypothesis may not be explicitly proven but is most probably the best guess. The third conclusion is that the currently available evidence does not permit a confident conclusion or a best guess, while the last conclusion is that the theory or hypothesis is false [ 1 ]. It is important not to present new information in the conclusion section which has link whatsoever with the rest of the manuscript. According to Harris et al. [ 90 ], the conclusions should, in essence, answer the question: if a reader were to remember one thing about the review, what would it be?

5.10. References

As it has been noted in different parts of this paper, authors must give the required credit to any work or source(s) of information that was included in the review article. This must include the in-text citations in the main body of the paper and the corresponding entries in the reference list. Ideally, this full bibliographical list is the last part of the review article, and it should contain all the books, book chapters, journal articles, reports, and other media, which were utilised in the manuscript. It has been noted that most journals and publishers have their own specific referencing styles which are all derived from the more popular styles such as the American Psychological Association (APA), Chicago, Harvard, Modern Language Association (MLA), and Vancouver styles. However, all these styles may be categorised into either the parenthetical or numerical referencing style. Although a few journals do not have strict referencing rules, it is the responsibility of the author to reference according to the style and instructions of the journal. Omissions and errors must be avoided at all costs, and this can be easily achieved by going over the references many times for due diligence [ 11 ]. According to Cronin et al. [ 12 ], a separate file for references can be created, and any work used in the manuscript can be added to this list immediately after being cited in the text [ 12 ]. In recent times, the emergence of various referencing management software applications such as Endnote, RefWorks, Mendeley, and Zotero has even made referencing easier. The majority of these software applications require little technical expertise, and many of them are free to use, while others may require a subscription. It is imperative, however, that even after using these software packages, the author must manually curate the references during the final draft, in order to avoid any errors, since these programs are not impervious to errors, particularly formatting errors.

6. Concluding Remarks

Writing a review article is a skill that needs to be learned; it is a rigorous but rewarding endeavour as it can provide a useful platform to project the emerging researcher or postgraduate student into the gratifying world of publishing. Thus, the reviewer must develop the ability to think critically, spot patterns in a large volume of information, and must be invested in writing without tiring. The prospective author must also be inspired and dedicated to the successful completion of the article while also ensuring that the review article is not just a mere list or summary of previous research. It is also important that the review process must be focused on the literature and not on the authors; thus, overt criticism of existing research and personal aspersions must be avoided at all costs. All ideas, sentences, words, and illustrations should be constructed in a way to avoid plagiarism; basically, this can be achieved by paraphrasing, summarising, and giving the necessary acknowledgments. Currently, there are many tools to track and detect plagiarism in manuscripts, ensuring that they fall within a reasonable similarity index (which is typically 15% or lower for most journals). Although the more popular of these tools, such as Turnitin and iThenticate, are subscription-based, there are many freely available web-based options as well. An ideal review article is supposed to motivate the research topic and describe its key concepts while delineating the boundaries of research. In this regard, experience-based information on how to methodologically develop acceptable and impactful review articles has been detailed in this paper. Furthermore, for a beginner, this guide has detailed “the why” and “the how” of authoring a good scientific review article. However, the information in this paper may as a whole or in parts be also applicable to other fields of research and to other writing endeavours such as writing literature review in theses, dissertations, and primary research articles. Finally, the intending authors must put all the basic rules of scientific writing and writing in general into cognizance. A comprehensive study of the articles cited within this paper and other related articles focused on scientific writing will further enhance the ability of the motivated beginner to deliver a good review article.

Acknowledgments

This work was supported by the National Research Foundation of South Africa under grant number UID 138097. The authors would like to thank the Durban University of Technology for funding the postdoctoral fellowship of the first author, Dr. Ayodeji Amobonye.

Data Availability

Conflicts of interest.

The authors declare that they have no conflicts of interest.

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Writing a Literature Review

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A literature review is a document or section of a document that collects key sources on a topic and discusses those sources in conversation with each other (also called synthesis ). The lit review is an important genre in many disciplines, not just literature (i.e., the study of works of literature such as novels and plays). When we say “literature review” or refer to “the literature,” we are talking about the research ( scholarship ) in a given field. You will often see the terms “the research,” “the scholarship,” and “the literature” used mostly interchangeably.

Where, when, and why would I write a lit review?

There are a number of different situations where you might write a literature review, each with slightly different expectations; different disciplines, too, have field-specific expectations for what a literature review is and does. For instance, in the humanities, authors might include more overt argumentation and interpretation of source material in their literature reviews, whereas in the sciences, authors are more likely to report study designs and results in their literature reviews; these differences reflect these disciplines’ purposes and conventions in scholarship. You should always look at examples from your own discipline and talk to professors or mentors in your field to be sure you understand your discipline’s conventions, for literature reviews as well as for any other genre.

A literature review can be a part of a research paper or scholarly article, usually falling after the introduction and before the research methods sections. In these cases, the lit review just needs to cover scholarship that is important to the issue you are writing about; sometimes it will also cover key sources that informed your research methodology.

Lit reviews can also be standalone pieces, either as assignments in a class or as publications. In a class, a lit review may be assigned to help students familiarize themselves with a topic and with scholarship in their field, get an idea of the other researchers working on the topic they’re interested in, find gaps in existing research in order to propose new projects, and/or develop a theoretical framework and methodology for later research. As a publication, a lit review usually is meant to help make other scholars’ lives easier by collecting and summarizing, synthesizing, and analyzing existing research on a topic. This can be especially helpful for students or scholars getting into a new research area, or for directing an entire community of scholars toward questions that have not yet been answered.

What are the parts of a lit review?

Most lit reviews use a basic introduction-body-conclusion structure; if your lit review is part of a larger paper, the introduction and conclusion pieces may be just a few sentences while you focus most of your attention on the body. If your lit review is a standalone piece, the introduction and conclusion take up more space and give you a place to discuss your goals, research methods, and conclusions separately from where you discuss the literature itself.

Introduction:

An introductory paragraph that explains what your working topic and thesis is
A forecast of key topics or texts that will appear in the review
Potentially, a description of how you found sources and how you analyzed them for inclusion and discussion in the review (more often found in published, standalone literature reviews than in lit review sections in an article or research paper)
Summarize and synthesize: Give an overview of the main points of each source and combine them into a coherent whole
Analyze and interpret: Don’t just paraphrase other researchers – add your own interpretations where possible, discussing the significance of findings in relation to the literature as a whole
Critically Evaluate: Mention the strengths and weaknesses of your sources
Write in well-structured paragraphs: Use transition words and topic sentence to draw connections, comparisons, and contrasts.

Conclusion:

Summarize the key findings you have taken from the literature and emphasize their significance
Connect it back to your primary research question

How should I organize my lit review?

Lit reviews can take many different organizational patterns depending on what you are trying to accomplish with the review. Here are some examples:

Chronological : The simplest approach is to trace the development of the topic over time, which helps familiarize the audience with the topic (for instance if you are introducing something that is not commonly known in your field). If you choose this strategy, be careful to avoid simply listing and summarizing sources in order. Try to analyze the patterns, turning points, and key debates that have shaped the direction of the field. Give your interpretation of how and why certain developments occurred (as mentioned previously, this may not be appropriate in your discipline — check with a teacher or mentor if you’re unsure).
Thematic : If you have found some recurring central themes that you will continue working with throughout your piece, you can organize your literature review into subsections that address different aspects of the topic. For example, if you are reviewing literature about women and religion, key themes can include the role of women in churches and the religious attitude towards women.
Qualitative versus quantitative research
Empirical versus theoretical scholarship
Divide the research by sociological, historical, or cultural sources
Theoretical : In many humanities articles, the literature review is the foundation for the theoretical framework. You can use it to discuss various theories, models, and definitions of key concepts. You can argue for the relevance of a specific theoretical approach or combine various theorical concepts to create a framework for your research.

What are some strategies or tips I can use while writing my lit review?

Any lit review is only as good as the research it discusses; make sure your sources are well-chosen and your research is thorough. Don’t be afraid to do more research if you discover a new thread as you’re writing. More info on the research process is available in our "Conducting Research" resources .

As you’re doing your research, create an annotated bibliography ( see our page on the this type of document ). Much of the information used in an annotated bibliography can be used also in a literature review, so you’ll be not only partially drafting your lit review as you research, but also developing your sense of the larger conversation going on among scholars, professionals, and any other stakeholders in your topic.

Usually you will need to synthesize research rather than just summarizing it. This means drawing connections between sources to create a picture of the scholarly conversation on a topic over time. Many student writers struggle to synthesize because they feel they don’t have anything to add to the scholars they are citing; here are some strategies to help you:

It often helps to remember that the point of these kinds of syntheses is to show your readers how you understand your research, to help them read the rest of your paper.
Writing teachers often say synthesis is like hosting a dinner party: imagine all your sources are together in a room, discussing your topic. What are they saying to each other?
Look at the in-text citations in each paragraph. Are you citing just one source for each paragraph? This usually indicates summary only. When you have multiple sources cited in a paragraph, you are more likely to be synthesizing them (not always, but often
Read more about synthesis here.

The most interesting literature reviews are often written as arguments (again, as mentioned at the beginning of the page, this is discipline-specific and doesn’t work for all situations). Often, the literature review is where you can establish your research as filling a particular gap or as relevant in a particular way. You have some chance to do this in your introduction in an article, but the literature review section gives a more extended opportunity to establish the conversation in the way you would like your readers to see it. You can choose the intellectual lineage you would like to be part of and whose definitions matter most to your thinking (mostly humanities-specific, but this goes for sciences as well). In addressing these points, you argue for your place in the conversation, which tends to make the lit review more compelling than a simple reporting of other sources.

Methodology
Open access
Published: 09 May 2024

Network meta-analysis for an ordinal outcome when outcome categorization varies across trials

Paul Morris 1 ,
Chong Wang ORCID: orcid.org/0000-0003-4489-4344 1 , 2 &
Annette O’Connor 2 , 3

Systematic Reviews volume 13 , Article number: 128 ( 2024 ) Cite this article

133 Accesses

Metrics details

Binary outcomes are likely the most common in randomized controlled trials, but ordinal outcomes can also be of interest. For example, rather than simply collecting data on diseased versus healthy study subjects, investigators may collect information on the severity of disease, with no disease, mild, moderate, and severe disease as possible levels of the outcome. While some investigators may be interested in all levels of the ordinal variable, others may combine levels that are not of particular interest. Therefore, when research synthesizers subsequently conduct a network meta-analysis on a network of trials for which an ordinal outcome was measured, they may encounter a network in which outcome categorization varies across trials.

The standard method for network meta-analysis for an ordinal outcome based on a multinomial generalized linear model is not designed to accommodate the multiple outcome categorizations that might occur across trials. In this paper, we propose a network meta-analysis model for an ordinal outcome that allows for multiple categorizations. The proposed model incorporates the partial information provided by trials that combine levels through modification of the multinomial likelihoods of the affected arms, allowing for all available data to be considered in estimation of the comparative effect parameters. A Bayesian fixed effect model is used throughout, where the ordinality of the outcome is accounted for through the use of the adjacent-categories logit link.

We illustrate the method by analyzing a real network of trials on the use of antibiotics aimed at preventing liver abscesses in beef cattle and explore properties of the estimates of the comparative effect parameters through simulation. We find that even with the categorization of the levels varying across trials, the magnitudes of the biases are relatively small and that under a large sample size, the root mean square errors become small as well.

Conclusions

Our proposed method to conduct a network meta-analysis for an ordinal outcome when the categorization of the outcome varies across trials, which utilizes the adjacent-categories logit link, performs well in estimation. Because the method considers all available data in a single estimation, it will be particularly useful to research synthesizers when the network of interest has only a limited number of trials for each categorization of the outcome.

Peer Review reports

Network meta-analysis (NMA) is an extension of traditional pairwise meta-analysis that allows for the simultaneous comparison of multiple interventions by utilizing direct and indirect evidence from a network of randomized clinical trials [ 1 ]. When the outcome of interest is categorical with more than two categories, the NMA is typically conducted through the use of a generalized linear model (GLM) where the random component is multinomial, as described by [ 2 ]. It is common to utilize some type of logit link in a multinomial GLM [ 3 ], under which the parameters of interest in the NMA correspond to log-odds ratios of subjects belonging to a given category versus another under a particular intervention relative to the network’s baseline intervention. The type of logit employed determines the outcome categories under consideration in these comparative effect parameters. When the outcome is unordered, the baseline-category logit is often used [ 4 ], and the log-odds ratios are parameterized in terms of non-baseline categories versus a selected baseline category. When the outcome is ordered, it is often referred to as an ordinal variable with the categories referred to as levels. One possible choice of link function for analyzing an ordinal outcome is the adjacent-categories logit [ 3 ], under which the log-odds ratios are parameterized in terms of adjoining levels. Analysts can select the logit link that best matches their question of interest given the properties of the outcome.

While ordinal outcomes must be comprised of mutually exclusive and exhaustive levels, reporting of data for such an outcome can depend on the question of interest being addressed in a given trial. This often leads to networks for which the categorization of the outcome varies across trials. For example, suppose that we are interested in the effects of a set of interventions on an ordinal outcome with four mutually exclusive and exhaustive levels, call them A, B, C, and D. While some trials report event counts for each of the four levels, others may report combined values for B and C or even for B, C, and D. Data combined in this fashion has been referred to as incomplete [ 5 ]. Note that incomplete data in the sense presented here is unique to categorical outcomes and is distinct from the phenomenon of missing data for which the values for some subjects are either not measured or not reported at all [ 6 , 7 , 8 ]. Trials that report incomplete data can still provide information that contributes to our knowledge of the underlying comparative effects. For example, if we are utilizing the adjacent-categories logit link, the combined data for levels B and C can inform the estimates of the log-odds ratios involving B versus A and D versus C. To maximize the utility of the network of trials, it would be advantageous to consider all of the available data in estimation, regardless of outcome categorization. Unfortunately, the standard multinomial GLM framework cannot simultaneously incorporate data from multiple categorizations without some modification.

The problem of multiple outcome categorizations within a network has been addressed by [ 5 ] for the case of an unordered outcome. They proposed an extension to the multinomial GLM framework wherein the form of the multinomial likelihood was modified to allow for outcome categories to be combined according to a trial’s categorization. Their model incorporates random comparative effects and utilizes the baseline-category logit link. However, the modified multinomial likelihood was structured around a specific example and is therefore not provided in a general form. In addition, the authors did not evaluate the performance of the model through simulation.

In this paper, we extend the method developed by [ 5 ] on several fronts. First, we take a step toward adapting the method for the case of an ordinal outcome by proposing a model that utilizes the adjacent-categories logit link rather than the baseline-category logit. The structure of the adjacent-categories logit link takes into account the ordering of the outcome [ 3 ] and is particularly useful if we are interested in the log-odds ratios pertaining to adjoining levels, as parameters representing these comparisons are directly included in the model. Second, we provide the general form of the modified multinomial likelihood that allows for any outcome categorization, whether the outcome is ordered or unordered. Throughout, we assume that the intervention effects are fixed, although this can be extended to the random effects case in a manner similar to that presented in [ 5 ], and use a Bayesian approach by conducting estimation through Markov Chain Monte Carlo (MCMC).

The remainder of the paper is organized as follows. The “ Methods ” section details the proposed model, including the general form of the modified multinomial likelihood, and describes the approach to estimation. The “ Application ” section illustrates a use case of the proposed model through an analysis of a real network of trials comparing the effects of various regimens of antibiotics on the prevention of liver abscesses in beef cattle, where the severity of the abscesses is reported on an ordinal scale. The “ Simulation ” section presents a simulation study that assesses the estimation performance of the proposed model, and the “ Discussion ” and “ Conclusions ” sections discuss and conclude.

This section specifies the proposed NMA model for an ordinal outcome when outcome categorization varies across trials. This includes detailing the general form of the modified multinomial likelihood and the model for the response probabilities that follows from use of the adjacent-categories logit link. The proposed model is a modified version of that detailed in [ 5 ] for an unordered outcome, with some of the notation borrowed from [ 2 ]. The Bayesian estimation approach used throughout, including the specification of priors and starting values, is also presented.

Accommodating multiple outcome categorizations

Here the general form of the modified multinomial likelihood that allows for any outcome categorization is specified. While the term levels will be used to denote the outcome categories, this notation is also applicable to the unordered case. Consider K interventions compared in I trials, where trial i has $n_i$ arms. Suppose that the outcome consists of M mutually exclusive and exhaustive levels, but that a given trial need not report data for each level separately. Rather, data for some levels may be reported together. That is, suppose that trial i collapses the M levels into $M_i \le M$ groups denoted by $A_{i,1}, A_{i,2}, \ldots , A_{i,M_i}$ that are mutually exclusive and exhaustive. Let $\left( r_{i,k,1},\ldots ,r_{i,k,M}\right)$ be the vector of true, but potentially unreported, counts for the M levels under trial i and intervention k . We can denote the total count for the $c^{th}$ combined category under trial i and intervention k as

where the separate counts $r_{i,k,m}$ for $m \in A_{i,c}$ are unreported if they belong to a group of combined levels. This notation for the grouping of levels is adapted from that given in [ 9 ] for the form of the collapsed and partitioned multinomial distribution. Note that this notation is applicable to both unordered and ordinal outcomes, but under the ordinal case it is reasonable to restrict groups to include only adjacent categories.

The reported data for intervention k in study i can then be modeled using a multinomial likelihood:

where $\varvec{p}_{i,k}$ and ${\textbf {z}}_{i,k}$ are the response probability and observed count vectors for intervention k in trial i , $p_{i,k,m}$ is the true response probability for intervention k and level m in study i , and $N_{i,k} = \sum _{c=1}^{M_i}z_{i,k,c} = \sum _{m=1}^{M}r_{i,k,m}$ . Since the levels are mutually exclusive and exhaustive, $\sum _{c=1}^{M_i}\sum _{m \in A_{i,c}}p_{i,k,m} = \sum _{m=1}^{M}p_{i,k,m} = 1$ for each trial i and intervention k .

Following independence, the likelihood for the entire network is then

where $\varvec{p}$ and ${\textbf {z}}$ are the response probability and observed count vectors for the entire network and $K_{i}$ denotes the group of $n_i$ interventions included in trial i .

The modified likelihood accommodates the reporting of data for combined levels through the incorporation of the total outcome counts and response probabilities of the respective levels. The trials that combine levels therefore provide partial information on the underlying response probabilities [ 5 ], allowing for all data available across the network to contribute to the estimation of the model parameters.

Model for the response probabilities

When working with an ordinal outcome, it is natural to be interested in comparisons of interventions that involve the underlying order. A link function should be selected such that it allows analysts to directly make those comparisons of interest. The cumulative logit and the adjacent-categories logit links are common choices for an ordinal outcome. However, if proportional odds are not assumed, use of the cumulative logit does not necessarily result in valid estimated response probabilities [ 3 ]. In the context of NMA, proportional odds implies that the comparative effects of interventions are identical for each of the level pairings considered under the chosen link function. The proportional odds assumption can be useful, particularly if there is reason to believe that the effects of interventions are similar across each of the level pairings, because it utilizes the ordinality of the outcome to reduce the number of parameters included in the model [ 3 ]. We leave the development of a procedure for determining when it is appropriate to assume proportional odds under the given framework for future work, and opt to utilize the adjacent-categories logit link under non-proportional odds for the remainder of this paper. Under the adjacent-categories logit link, the comparative effects are log-odds ratios of a subject belonging to a given level relative to the level below it. This could be of interest, for example, if we have a network where the outcome consists of the severity of disease ranging from healthy to severe. The estimates of the comparative effects would then provide insight on how interventions affect the odds of a subject belonging to the mild relative to the healthy state, the moderate relative to the mild state, and the severe relative to the moderate state. Since the adjacent-categories logit and baseline-category logit are functionally reparameterizations of each other [ 3 ], such comparisons could be made under the baseline-category logit link indirectly. However, the use of the adjacent-categories logit puts parameters corresponding to the comparisons of interest directly in the model. This approach can be helpful when specifying priors, making inferences, and diagnosing problems with estimation.

Since each trial does not necessarily include each of the K interventions, some additional notation is necessary. An overall baseline intervention for the network, b , must be selected. This will often correspond to a placebo or standard therapy group. Each trial i also has a trial-specific baseline intervention, $b_i$ , which will be the same as b if $b \in K_i$ . Then the response probabilities can be modeled as

where $I(\cdot )$ denotes the indicator function, and

The logit described in Eq. 4 can be interpreted as the log-odds of a subject belonging to level m versus $m-1$ under trial i and intervention k . Under Eq. 4 , the $\mu _{i,m}$ correspond to trial-specific baselines representing the log-odds of level m versus level $m-1$ under study i ’s baseline intervention $b_i$ . These are regarded as nuisance parameters and serve only to set up the contrast needed to include the parameters corresponding to the comparative effects. The $d_{b_i,k,m}$ represents the log-odds ratio of a subject belonging to category m versus $m-1$ under intervention k relative to the trial-specific baseline $b_i$ . These are included in Eq. 4 only if $k \ne b_i$ , as if $k = b_i$ then $\mu _{i,m}$ represents the corresponding logit on its own. Following from the consistency assumption (see [ 10 ] for an overview of the assumptions commonly made in NMA),

where $d_{k,m}$ represents the log-odds ratio of a subject belonging to category m versus $m-1$ under intervention k relative to the overall baseline intervention b . The $d_{k,m}$ are the parameters of interest and do not vary across trials under the assumption of fixed intervention effects. Under the consistency assumption, the comparative effect between any two interventions $k_1$ and $k_2$ is $d_{k_1, k_2, m} = d_{k_2,m} - d_{k_1,m}$ .

Expressions for the response probabilities can be obtained through an application of the inverse adjacent-categories logit function [ 11 ] to Eqs. 4 and 5 :

Bayesian implementation

The model parameters are estimated using MCMC via the JAGS software package [ 12 ]. The Bayesian approach is advantageous for the proposed method, as it allows for the specification of informative priors to help overcome the lack of identifiability of some of the trial-specific baseline parameters.

Prior specification

In order to implement the Bayesian approach, priors need to be assigned to the parameters in the model. Since we are assuming fixed intervention effects, we need only consider each of the $\mu _{i,m}$ and $d_{k,m}$ . Identifiability of the $d_{k,m}$ requires that for each adjacent pair of levels there exists a path of comparisons that connects all of the interventions such that in each comparison the event counts for the two levels are reported separately. Assuming that this condition holds, we can assign these parameters non-informative $\text {Normal}(0, 1,000,000)$ priors as was done in [ 5 ].

Recall that the $\mu _{i,m}$ are trial-specific baselines representing the log-odds of a subject belonging to level m versus $m-1$ under trial i ’s baseline intervention $b_i$ . Since any combination of adjacent levels is allowed in the observed data, for a given trial, separate event counts for levels m and $m-1$ may not be reported. This means that there will not be data available to estimate some of the $\mu _{i,m}$ parameters. Stronger priors can be used to help overcome this lack of identifiability. We propose the following procedure to specify priors for the $\mu _{i,m}$ . For the group of trials T that report separate event counts for levels m and $m-1$ under trial-specific baseline intervention $b_i$ :

Calculate the empirical log-odds for category m versus $m-1$ under intervention $b_i$ from the available data. In the specified notation, these would take the form $y_i = log(r_{i,b_i,m}/r_{i,b_i,m-1})$ for trials $i \in T$ . Note that if either of the event counts is 0 for trial i , we add 0.5 to each count to ensure that the empirical log-odds fall on the real line.

Fit the following Bayesian model using the $y_i$ from the previous step as data: $y_i {\mathop {\sim }\limits ^{iid}} \text {Normal}(\mu , \sigma ^2)$ with priors $\mu \sim Normal(0, 1000)$ and $\sigma \sim Uniform(0, 5)$ . This can be done using JAGS via the rjags R package [ 13 ], where 10,000 iterations are run for each of burn-in and sampling. Note that this step is adapted from the estimation of the baseline-effects model under NMA for a binary outcome presented in [ 14 ].

Letting $\hat{\mu }$ and $\hat{\sigma }^2$ denote the posterior means of $\mu$ and $\sigma ^2$ obtained in step 2, assign the prior $\mu _{i,m} \sim Normal\left(\hat{\mu }, \hat{\sigma }^2\right)$ for each $i \in T$ .

Selection of starting values

Selecting suitable starting values is important to ensure proper behavior of the MCMC chains. Schmid et al. [ 5 ] proposes a method for selecting dispersed starting values under the baseline-category logit link. This procedure was later implemented in the BNMA R package [ 15 ]. We modify this procedure for use with the adjacent-categories logit link by substituting the empirical adjacent-categories log-odds for the empirical baseline-category log-odds in the described regression.

Parameter estimation

Estimation was achieved through MCMC using the JAGS software, where we interfaced with JAGS via the rjags R package. Four MCMC chains were used, and proper convergence and mixing of the chains were monitored through the Gelman-Rubin diagnostic [ 16 ] and examination of the trace plots.

Application

In this section, the use of the proposed model is illustrated through the analysis of a network of studies examining the effects of several antibiotic regimens on the prevention of liver abscesses in beef cattle. Many studies in the veterinary literature have compared the efficacy of various interventions on this outcome, but synthesis of this research has proved difficult because the categorization of the outcome varies across trials. Abscess severity is often measured using an ordinal scale containing four levels: healthy (H), one or two small abscesses (A−), two to four small abscesses (A), and one or more large abscesses (A+) [ 17 , 18 ]. This ordinal scale is well established in the beef cattle industry. However, because the economic impact of liver abscesses is mainly linked to the A+ level, some investigators combined levels A− and A [ 19 , 20 ], resulting in a three-level outcome variable. This three-level scale is currently used by the well-known Elanco Liver Check Service [ 21 ]. Still other investigators report the presence of any abscess regardless of severity, combining A−, A, and A+ [ 22 , 23 ], resulting in a two-level outcome variable. To control liver abscesses, in-feed antibiotics are used. Currently, in-feed tylosin phosphate, an antibiotic in the same family as erythromycin, is the primary approach to the prevention of liver abscesses. However, over the years numerous approaches to control have been evaluated including diets, other antibiotics, non-antibiotic additives, ionophores, and other regimens of tylosin.

The data for this network are a subset of that obtained from a systematic review of interventions aimed at preventing liver abscesses in cattle (the review protocol of which is available at https://syreaf.org/protocols/ ). For the purposes of this project, only four interventions are included in the network presented here to enable focus on the methodological issue of interest. Three of the intervention groups are regimens of the antibiotics tylosin phosphate or virginiamycin while the fourth is a placebo group. An example of a trial identified by the review but excluded in this study is [ 24 ]. The purpose of this trial was to evaluate the effect of a phytogenic feed additive (Digestarom; Biomin, Getzersdorf, Austria) on multiple outcomes including liver abscesses in finishing steers. Since the trial did not examine any of the tylosin phosphate or virginiamycin regimens of interest it was excluded from our network.

For the trials included in the network, we defined a placebo arm as any trial arm that did not contain tylosin phosphate or virginiamycin. Placebo arms contained any level of monensin or diet composition. Monensin is an ionophore administered in feed that promotes the efficient use of feedstuffs and is not considered to have any impact on liver abscesses. As many trials included multiple such arms, the data from these arms were combined to create a single placebo arm per trial. To illustrate this approach we use a trial published in [ 17 ]. This trial was a 2 by 3 factorial design with one factor being diet: based on steam-flaked corn finishing diet (SFC) or SFC plus 25% (dry basis) corn wet distillers grains with solubles (WDGS). The second factor was feed additives: no added antibiotics (NONE), 300 mg of monensin daily (MON), or 300 mg of monensin + 90 mg of tylosin phosphate daily (MON+TYL). Our approach to handling such a trial was to combine the data for the NONE + SFC, NONE + WDGS , MON + SFC, and MON + WDG arms into a single placebo arm. The antibiotic arm (tylosin phosphate) was created by combing the data from the (MON + TYL) + SFC and (MON + TYL) + WDGS arms. The treatments were fed from arrival to slaughter, i.e., 150 days.

Tylosin phosphate arms were categorized based on dosing regimens as follows:

Protocols that began the feeding period without tylosin phosphate and started to feed constantly late in the feed period (latestart)

Protocols that began the feeding period with tylosin phosphate and ended the feeding period without tylosin phosphate (earlyfinish)

Protocols that did use tylosin phosphate for the entire feeding period but limited the period to less than or equal to 100 days (short)

Protocols that did use tylosin phosphate for the entire feeding period but that feeding period was more than 100 days (long)

Protocols that did use tylosin phosphate for the entire period but intermittently (intermittent).

An example of the use of this approach to categorize tylosin regimens is provided by [ 25 ], which investigated management strategies that reduce in-feed tylosin phosphate in the control of liver abscesses in feedlot cattle. A total of 7576 crossbred yearlings were allocated to the trial (approximately 253 animals/pen with 10 replicate pens per treatment) and individually randomized to one of three treatments: tylosin phosphate (11 ppm) was included in-feed (1) for the first 125 days on feed (DOF) (earlyfinish) (2) for DOF 41 to 161 (latestart) or (3) for the entire feeding period for DOF 0 to 161 (long). However, for this project, we only included arms corresponding to the “long” regimen as a means of keeping the illustrative data set simple. This is also the registered dose, while the others are exploratory.

Virginiamycin arms were categorized based on two dose levels: less than 15 mg/kg, and greater than or equal to 15 mg/kg. An example of an application of this grouping scheme follows from [ 26 ], which fed cattle a four-level range of virginiamycin (0, 10, 25, and 50 mg/kg) over multiple trials throughout a 245 day growing-finishing period. For this trial, the 0 mg/kg arm was designated as the placebo, 10 mg/kg arm was designated as being less than 15 mg/kg, and the data for the 25 mg/kg and 50 mg/kg arms were combined into a single arm with greater than 15 mg/kg virginiamycin.

Figure 1 presents a diagram of the network. Note that every trial included a placebo group, and that the tylosin phosphate regimen is included in a large number of trials relative to the virginiamycin regimens. Also note that the tylosin phosphate regimen is not directly compared with either of the virginiamycin dosing regimens. Each of the three liver abscess categorizations detailed in the first paragraph of this section is present in the network. Table 1 details the frequencies of these categorizations. While 12 of the 22 trials comparing tylosin phosphate to the placebo reported complete data (4 levels), complete data was available in only four of the eight trials including either of the virginiamycin regimens. The remaining four trials that included either of the virginiamycin regimens combined A−, A, and A+ in their reporting. There is thus substantially less data available to estimate the comparative effects involving virginiamycin compared to those for tylosin phosphate.

Diagram of the liver abscess trial network. Nodes are interventions and edges are direct comparisons. The size of the nodes and the numbers in parentheses indicate the number of trials that include each intervention, while the edge width indicates the number of direct comparisons made between each intervention

Estimation was conducted as described in the “ Bayesian implementation ” section. Here the model parameters were estimated using 50,000 iterations for each of burn-in and sampling. Table 2 displays the point estimates and 95% credible intervals for each of the basic comparative effect parameters on the log-odds ratio and odds ratio scales. A negative estimate on the log-odds ratio scale means that a subject is estimated to be relatively more likely to belong to the lower disease level than the higher one under the noted intervention compared to under the placebo. We note that the 95% credible intervals are quite wide for the comparative effects associated with virginiamycin due to the limited amount of data on that antibiotic in the network.

In this section, properties of the estimates of the comparative effect parameters are evaluated through simulation under two scenarios. In the first, we treat the point estimates obtained in the “ Application ” section as the true values for the parameters and use these values to repeatedly regenerate the data for the liver abscess network. The estimates obtained by analyzing the regenerated datasets can then be used to calculate bias, root mean square error (RMSE), and coverage probability of the credible intervals. The second scenario is similar to the first, except that here in the regeneration step data for each study is generated ten times as if it came from ten different studies. This results in simulated datasets that are ten times larger than those in the first scenario, which allows for the evaluation of large-sample estimation performance.

The simulation procedure for the first scenario is as follows:

Obtain the posterior means for each parameter from the existing NMA (values for the comparative effects are given in Table 2 , while those for the trial-specific baselines are not shown). For each trial i , intervention k and outcome level $m = 2,\ldots , M$ that occurs in the network, let $\hat{\mu }_{i,m}$ and $\hat{d}_{k,m}$ denote the corresponding posterior means.

For each trial i , intervention k and outcome level $m = 2,\ldots , M$ in the network, calculate $\hat{\theta }_{i,k,m} = \hat{\mu }_{i,m} + \hat{d}_{b_i,k,m}$ where $\hat{d}_{b_i,k,m}$ is obtained by using the estimated comparative effects in Eq. 6 , i.e., the consistency assumption. Then obtain values for the multinomial response probabilities, denoted by $\hat{p}_{i,k,m}$ , using $\hat{\theta }_{i,k,m}$ in Eqs. 7 and 8 .

Complete the following 1000 times:

Generate the complete data for the network using the calculated probabilities. For each trial i and intervention k in $K_i$ : $(r_{i,k,1},\ldots ,r_{i,k,M}) \sim \text {Multinomial}(N_{i,k}, (\hat{p}_{i,k,1},\ldots ,\hat{p}_{i,k,M}))$ .

Combine the outcome data where necessary as indicated by the existing network. This gives the observed data in the form of the $z_{i,k,c}$ , where $z_{i,k,c} = \sum _{m \in A_{i,c}}r_{i,k,m}$ and $A_{i,c}$ is the $c^{th}$ group of outcome levels for trial i .

Conduct the analysis on the generated dataset using the proposed model as was done in the “ Application ” section. Here 25,000 iterations were used for each of burn-in and sampling to ensure reasonable computation time. Record the posterior means of the $d_{k,m}$ , the comparative effect parameters of interest.

Calculate the bias, RMSE, and coverage probability for each of the $d_{k,m}$ using the posterior means as the point estimates.

The simulation results for the first scenario are displayed in Table 3 . We see that the magnitude of the biases is relatively small and consistent across each of the comparative effect parameters. Given the lack of available data with which to estimate the trial-specific baseline parameters in some trials, some bias is expected as posterior draws for the baseline parameters that fall far from the true values will inevitably affect the estimation of the comparative effects. The use of more informative priors for the trial-specific baseline parameters as described in the “ Prior specification ” section helps limit the bias relative to using non-informative priors. The RMSEs are somewhat large due to the limited amount of data available to estimate many of these comparisons, particularly for those involving either of the virginiamycin regimens. As we will see in the simulation results for the second scenario, the magnitude of the RMSEs can be reduced if more data is available. Finally, it is clear that the proposed model achieves coverage probabilities close to the nominal value.

Scenario II

For the second scenario, the simulation procedure is identical to that used in the first except that in step (3), each trial in the existing network is used to generate data for ten separate trials rather than one. We thus generate datasets that are ten times as large as those under the first scenario. Results of the simulations under the second scenario are available in Table 4 . Note that the biases are of similar magnitude to those seen under the first scenario. While the datasets are ten times as large, there are also ten times as many trials, and thus we have not circumvented the issue brought on by the trial-specific baseline parameters that was noted in the first scenario. However, the magnitude of the RMSEs is substantially reduced, including those corresponding to comparative effects involving the virginiamycin interventions. It is worth noting here that the coverage probabilities are slightly lower than in the previous scenario. Since more data is available to estimate each of these comparisons, the credible intervals are narrower. In conjunction with the slight bias introduced through the trial-specific baseline parameters, the narrower intervals result in the true values falling outside of the given bounds at a higher rate.

In this paper we proposed a fixed effect multinomial NMA model for an ordinal outcome that allows for multiple outcome categorizations within a network. The proposed model is a modification of that presented in [ 5 ] for an unordered categorical outcome. These models are particularly useful when working with sparse networks, which are commonly encountered and can affect the quality of comparative effect estimates in terms of both precision and power. Because the models simultaneously accommodate trials with different outcome categorizations, they allow for the consideration of all available data in the estimation of the comparative effects. Practitioners can therefore avoid contributing to the sparsity of the network by excluding valuable information.

Furthermore, when working with an ordinal outcome, it is often desirable to compare interventions in such a way that the ordering is recognized. While it would be possible to use the method of [ 5 ] to analyze a network with an ordinal outcome, the resulting comparative effects would not directly recognize the ordinality. The adjacent-categories logit link incorporates the ordering into the comparative effect parameters and is an appropriate choice in many applications. It is possible to back out the adjacent-category comparative effect estimates from those of the baseline-category model through the relationship between the two logit functions [ 3 ], but including the adjacent-category comparative effects directly in the model makes specifying priors, conducting inference, and optimizing estimation more straightforward.

As with any method, there are some limitations that are important to keep in mind. While the simulations showed that the estimates of the comparative effects behave reasonably well, the lack of data with which to estimate some of the trial-specific baseline parameters introduces some bias that is not eliminated as sample size increases (see Tables 3 and 4 ). An empirical approach to specifying informative priors for these trial-specific baseline parameters was used in an attempt to keep the bias small. This approach limits the bias relative to using non-informative priors but could potentially be optimized even further. It is important to note that there is then a potential trade-off between limiting sparsity and introducing bias that comes with allowing for multiple outcome categorizations. It is possible that the standard multinomial NMA model could be the better choice for some networks with sizable amounts of data.

It is also important to ensure that the estimation procedure behaves as intended. Even with sensibly chosen priors and starting values, the complexity of NMA models can make estimation through MCMC difficult. For example, in the second simulation scenario, the adaptation phase run by JAGS was not completed for many of the generated datasets even after 25,000 iterations. Adaptation can affect the behavior of the samplers employed by JAGS. Care therefore needed to be taken to ensure that the chains were run long enough such that mixing and convergence were achieved and effective sample sizes were reasonably high.

Finally, additional developments not implemented here can increase the utility of the proposed method. For example, the proportional odds assumption, which states that the comparative effect parameters for a given intervention are the same across the different level pairings, could be reasonable for some applications with ordinal outcomes. The assumption exploits the ordinality of the outcome to reduce the number of parameters included in the model [ 3 ]. However, it is a strong assumption to make and the researchers would need to be sure that it is appropriate for a given level pairing before implementing it. The development of a procedure to determine if the proportional odds assumption is appropriate under the adjacent-categories logit link function would allow for its incorporation into the proposed model. In addition, the proposed model could be extended through the use of other link functions. For example, the cumulative logit link might be of interest for a given application and could be used if the proportional odds assumption was determined to be appropriate for that structure. An extension allowing for random intervention effects could also improve the fit of the proposed method for many networks.

In conclusion, we have proposed a multinomial NMA model for ordinal outcomes that can simultaneously handle multiple outcome categorizations, thereby ensuring that data from all of the trials included in a network can be used during estimation. The use of the adjacent-categories logit link incorporates the ordering of the outcome into the comparative effect parameters, and simulations showed that the model generally performs well with respect to estimation. The inclusion of the general form of the modified multinomial likelihood that allows for any combination of levels and R functions linked to below that can be used to implement the method should allow for its use in a wide range of applications. Moreover, there is substantial room for further development that can take fuller advantage of the ordinality of the outcome through the proportional odds assumption and the utilization of additional link functions.

Availability of data and materials

The dataset analyzed in the application section of this article as well as R functions that can be used to implement the proposed method are available at https://github.com/psmorris15/ordinal_NMA .

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Cultural Relativity and Acceptance of Embryonic Stem Cell Research

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There is a debate about the ethical implications of using human embryos in stem cell research, which can be influenced by cultural, moral, and social values. This paper argues for an adaptable framework to accommodate diverse cultural and religious perspectives. By using an adaptive ethics model, research protections can reflect various populations and foster growth in stem cell research possibilities.

INTRODUCTION

Stem cell research combines biology, medicine, and technology, promising to alter health care and the understanding of human development. Yet, ethical contention exists because of individuals’ perceptions of using human embryos based on their various cultural, moral, and social values. While these disagreements concerning policy, use, and general acceptance have prompted the development of an international ethics policy, such a uniform approach can overlook the nuanced ethical landscapes between cultures. With diverse viewpoints in public health, a single global policy, especially one reflecting Western ethics or the ethics prevalent in high-income countries, is impractical. This paper argues for a culturally sensitive, adaptable framework for the use of embryonic stem cells. Stem cell policy should accommodate varying ethical viewpoints and promote an effective global dialogue. With an extension of an ethics model that can adapt to various cultures, we recommend localized guidelines that reflect the moral views of the people those guidelines serve.

Stem cells, characterized by their unique ability to differentiate into various cell types, enable the repair or replacement of damaged tissues. Two primary types of stem cells are somatic stem cells (adult stem cells) and embryonic stem cells. Adult stem cells exist in developed tissues and maintain the body’s repair processes. [1] Embryonic stem cells (ESC) are remarkably pluripotent or versatile, making them valuable in research. [2] However, the use of ESCs has sparked ethics debates. Considering the potential of embryonic stem cells, research guidelines are essential. The International Society for Stem Cell Research (ISSCR) provides international stem cell research guidelines. They call for “public conversations touching on the scientific significance as well as the societal and ethical issues raised by ESC research.” [3] The ISSCR also publishes updates about culturing human embryos 14 days post fertilization, suggesting local policies and regulations should continue to evolve as ESC research develops. [4] Like the ISSCR, which calls for local law and policy to adapt to developing stem cell research given cultural acceptance, this paper highlights the importance of local social factors such as religion and culture.

I. Global Cultural Perspective of Embryonic Stem Cells

Views on ESCs vary throughout the world. Some countries readily embrace stem cell research and therapies, while others have stricter regulations due to ethical concerns surrounding embryonic stem cells and when an embryo becomes entitled to moral consideration. The philosophical issue of when the “someone” begins to be a human after fertilization, in the morally relevant sense, [5] impacts when an embryo becomes not just worthy of protection but morally entitled to it. The process of creating embryonic stem cell lines involves the destruction of the embryos for research. [6] Consequently, global engagement in ESC research depends on social-cultural acceptability.

a. US and Rights-Based Cultures

In the United States, attitudes toward stem cell therapies are diverse. The ethics and social approaches, which value individualism, [7] trigger debates regarding the destruction of human embryos, creating a complex regulatory environment. For example, the 1996 Dickey-Wicker Amendment prohibited federal funding for the creation of embryos for research and the destruction of embryos for “more than allowed for research on fetuses in utero.” [8] Following suit, in 2001, the Bush Administration heavily restricted stem cell lines for research. However, the Stem Cell Research Enhancement Act of 2005 was proposed to help develop ESC research but was ultimately vetoed. [9] Under the Obama administration, in 2009, an executive order lifted restrictions allowing for more development in this field. [10] The flux of research capacity and funding parallels the different cultural perceptions of human dignity of the embryo and how it is socially presented within the country’s research culture. [11]

b. Ubuntu and Collective Cultures

African bioethics differs from Western individualism because of the different traditions and values. African traditions, as described by individuals from South Africa and supported by some studies in other African countries, including Ghana and Kenya, follow the African moral philosophies of Ubuntu or Botho and Ukama , which “advocates for a form of wholeness that comes through one’s relationship and connectedness with other people in the society,” [12] making autonomy a socially collective concept. In this context, for the community to act autonomously, individuals would come together to decide what is best for the collective. Thus, stem cell research would require examining the value of the research to society as a whole and the use of the embryos as a collective societal resource. If society views the source as part of the collective whole, and opposes using stem cells, compromising the cultural values to pursue research may cause social detachment and stunt research growth. [13] Based on local culture and moral philosophy, the permissibility of stem cell research depends on how embryo, stem cell, and cell line therapies relate to the community as a whole. Ubuntu is the expression of humanness, with the person’s identity drawn from the “’I am because we are’” value. [14] The decision in a collectivistic culture becomes one born of cultural context, and individual decisions give deference to others in the society.

Consent differs in cultures where thought and moral philosophy are based on a collective paradigm. So, applying Western bioethical concepts is unrealistic. For one, Africa is a diverse continent with many countries with different belief systems, access to health care, and reliance on traditional or Western medicines. Where traditional medicine is the primary treatment, the “’restrictive focus on biomedically-related bioethics’” [is] problematic in African contexts because it neglects bioethical issues raised by traditional systems.” [15] No single approach applies in all areas or contexts. Rather than evaluating the permissibility of ESC research according to Western concepts such as the four principles approach, different ethics approaches should prevail.

Another consideration is the socio-economic standing of countries. In parts of South Africa, researchers have not focused heavily on contributing to the stem cell discourse, either because it is not considered health care or a health science priority or because resources are unavailable. [16] Each country’s priorities differ given different social, political, and economic factors. In South Africa, for instance, areas such as maternal mortality, non-communicable diseases, telemedicine, and the strength of health systems need improvement and require more focus [17] Stem cell research could benefit the population, but it also could divert resources from basic medical care. Researchers in South Africa adhere to the National Health Act and Medicines Control Act in South Africa and international guidelines; however, the Act is not strictly enforced, and there is no clear legislation for research conduct or ethical guidelines. [18]

Some parts of Africa condemn stem cell research. For example, 98.2 percent of the Tunisian population is Muslim. [19] Tunisia does not permit stem cell research because of moral conflict with a Fatwa. Religion heavily saturates the regulation and direction of research. [20] Stem cell use became permissible for reproductive purposes only recently, with tight restrictions preventing cells from being used in any research other than procedures concerning ART/IVF. Their use is conditioned on consent, and available only to married couples. [21] The community's receptiveness to stem cell research depends on including communitarian African ethics.

c. Asia

Some Asian countries also have a collective model of ethics and decision making. [22] In China, the ethics model promotes a sincere respect for life or human dignity, [23] based on protective medicine. This model, influenced by Traditional Chinese Medicine (TCM), [24] recognizes Qi as the vital energy delivered via the meridians of the body; it connects illness to body systems, the body’s entire constitution, and the universe for a holistic bond of nature, health, and quality of life. [25] Following a protective ethics model, and traditional customs of wholeness, investment in stem cell research is heavily desired for its applications in regenerative therapies, disease modeling, and protective medicines. In a survey of medical students and healthcare practitioners, 30.8 percent considered stem cell research morally unacceptable while 63.5 percent accepted medical research using human embryonic stem cells. Of these individuals, 89.9 percent supported increased funding for stem cell research. [26] The scientific community might not reflect the overall population. From 1997 to 2019, China spent a total of $576 million (USD) on stem cell research at 8,050 stem cell programs, increased published presence from 0.6 percent to 14.01 percent of total global stem cell publications as of 2014, and made significant strides in cell-based therapies for various medical conditions. [27] However, while China has made substantial investments in stem cell research and achieved notable progress in clinical applications, concerns linger regarding ethical oversight and transparency. [28] For example, the China Biosecurity Law, promoted by the National Health Commission and China Hospital Association, attempted to mitigate risks by introducing an institutional review board (IRB) in the regulatory bodies. 5800 IRBs registered with the Chinese Clinical Trial Registry since 2021. [29] However, issues still need to be addressed in implementing effective IRB review and approval procedures.

The substantial government funding and focus on scientific advancement have sometimes overshadowed considerations of regional cultures, ethnic minorities, and individual perspectives, particularly evident during the one-child policy era. As government policy adapts to promote public stability, such as the change from the one-child to the two-child policy, [30] research ethics should also adapt to ensure respect for the values of its represented peoples.

Japan is also relatively supportive of stem cell research and therapies. Japan has a more transparent regulatory framework, allowing for faster approval of regenerative medicine products, which has led to several advanced clinical trials and therapies. [31] South Korea is also actively engaged in stem cell research and has a history of breakthroughs in cloning and embryonic stem cells. [32] However, the field is controversial, and there are issues of scientific integrity. For example, the Korean FDA fast-tracked products for approval, [33] and in another instance, the oocyte source was unclear and possibly violated ethical standards. [34] Trust is important in research, as it builds collaborative foundations between colleagues, trial participant comfort, open-mindedness for complicated and sensitive discussions, and supports regulatory procedures for stakeholders. There is a need to respect the culture’s interest, engagement, and for research and clinical trials to be transparent and have ethical oversight to promote global research discourse and trust.

d. Middle East

Countries in the Middle East have varying degrees of acceptance of or restrictions to policies related to using embryonic stem cells due to cultural and religious influences. Saudi Arabia has made significant contributions to stem cell research, and conducts research based on international guidelines for ethical conduct and under strict adherence to guidelines in accordance with Islamic principles. Specifically, the Saudi government and people require ESC research to adhere to Sharia law. In addition to umbilical and placental stem cells, [35] Saudi Arabia permits the use of embryonic stem cells as long as they come from miscarriages, therapeutic abortions permissible by Sharia law, or are left over from in vitro fertilization and donated to research. [36] Laws and ethical guidelines for stem cell research allow the development of research institutions such as the King Abdullah International Medical Research Center, which has a cord blood bank and a stem cell registry with nearly 10,000 donors. [37] Such volume and acceptance are due to the ethical ‘permissibility’ of the donor sources, which do not conflict with religious pillars. However, some researchers err on the side of caution, choosing not to use embryos or fetal tissue as they feel it is unethical to do so. [38]

Jordan has a positive research ethics culture. [39] However, there is a significant issue of lack of trust in researchers, with 45.23 percent (38.66 percent agreeing and 6.57 percent strongly agreeing) of Jordanians holding a low level of trust in researchers, compared to 81.34 percent of Jordanians agreeing that they feel safe to participate in a research trial. [40] Safety testifies to the feeling of confidence that adequate measures are in place to protect participants from harm, whereas trust in researchers could represent the confidence in researchers to act in the participants’ best interests, adhere to ethical guidelines, provide accurate information, and respect participants’ rights and dignity. One method to improve trust would be to address communication issues relevant to ESC. Legislation surrounding stem cell research has adopted specific language, especially concerning clarification “between ‘stem cells’ and ‘embryonic stem cells’” in translation. [41] Furthermore, legislation “mandates the creation of a national committee… laying out specific regulations for stem-cell banking in accordance with international standards.” [42] This broad regulation opens the door for future global engagement and maintains transparency. However, these regulations may also constrain the influence of research direction, pace, and accessibility of research outcomes.

e. Europe

In the European Union (EU), ethics is also principle-based, but the principles of autonomy, dignity, integrity, and vulnerability are interconnected. [43] As such, the opportunity for cohesion and concessions between individuals’ thoughts and ideals allows for a more adaptable ethics model due to the flexible principles that relate to the human experience The EU has put forth a framework in its Convention for the Protection of Human Rights and Dignity of the Human Being allowing member states to take different approaches. Each European state applies these principles to its specific conventions, leading to or reflecting different acceptance levels of stem cell research. [44]

For example, in Germany, Lebenzusammenhang , or the coherence of life, references integrity in the unity of human culture. Namely, the personal sphere “should not be subject to external intervention.” [45] Stem cell interventions could affect this concept of bodily completeness, leading to heavy restrictions. Under the Grundgesetz, human dignity and the right to life with physical integrity are paramount. [46] The Embryo Protection Act of 1991 made producing cell lines illegal. Cell lines can be imported if approved by the Central Ethics Commission for Stem Cell Research only if they were derived before May 2007. [47] Stem cell research respects the integrity of life for the embryo with heavy specifications and intense oversight. This is vastly different in Finland, where the regulatory bodies find research more permissible in IVF excess, but only up to 14 days after fertilization. [48] Spain’s approach differs still, with a comprehensive regulatory framework. [49] Thus, research regulation can be culture-specific due to variations in applied principles. Diverse cultures call for various approaches to ethical permissibility. [50] Only an adaptive-deliberative model can address the cultural constructions of self and achieve positive, culturally sensitive stem cell research practices. [51]

II. Religious Perspectives on ESC

Embryonic stem cell sources are the main consideration within religious contexts. While individuals may not regard their own religious texts as authoritative or factual, religion can shape their foundations or perspectives.

The Qur'an states:

“And indeed We created man from a quintessence of clay. Then We placed within him a small quantity of nutfa (sperm to fertilize) in a safe place. Then We have fashioned the nutfa into an ‘alaqa (clinging clot or cell cluster), then We developed the ‘alaqa into mudgha (a lump of flesh), and We made mudgha into bones, and clothed the bones with flesh, then We brought it into being as a new creation. So Blessed is Allah, the Best of Creators.” [52]

Many scholars of Islam estimate the time of soul installment, marked by the angel breathing in the soul to bring the individual into creation, as 120 days from conception. [53] Personhood begins at this point, and the value of life would prohibit research or experimentation that could harm the individual. If the fetus is more than 120 days old, the time ensoulment is interpreted to occur according to Islamic law, abortion is no longer permissible. [54] There are a few opposing opinions about early embryos in Islamic traditions. According to some Islamic theologians, there is no ensoulment of the early embryo, which is the source of stem cells for ESC research. [55]

In Buddhism, the stance on stem cell research is not settled. The main tenets, the prohibition against harming or destroying others (ahimsa) and the pursuit of knowledge (prajña) and compassion (karuna), leave Buddhist scholars and communities divided. [56] Some scholars argue stem cell research is in accordance with the Buddhist tenet of seeking knowledge and ending human suffering. Others feel it violates the principle of not harming others. Finding the balance between these two points relies on the karmic burden of Buddhist morality. In trying to prevent ahimsa towards the embryo, Buddhist scholars suggest that to comply with Buddhist tenets, research cannot be done as the embryo has personhood at the moment of conception and would reincarnate immediately, harming the individual's ability to build their karmic burden. [57] On the other hand, the Bodhisattvas, those considered to be on the path to enlightenment or Nirvana, have given organs and flesh to others to help alleviate grieving and to benefit all. [58] Acceptance varies on applied beliefs and interpretations.

Catholicism does not support embryonic stem cell research, as it entails creation or destruction of human embryos. This destruction conflicts with the belief in the sanctity of life. For example, in the Old Testament, Genesis describes humanity as being created in God’s image and multiplying on the Earth, referencing the sacred rights to human conception and the purpose of development and life. In the Ten Commandments, the tenet that one should not kill has numerous interpretations where killing could mean murder or shedding of the sanctity of life, demonstrating the high value of human personhood. In other books, the theological conception of when life begins is interpreted as in utero, [59] highlighting the inviolability of life and its formation in vivo to make a religious point for accepting such research as relatively limited, if at all. [60] The Vatican has released ethical directives to help apply a theological basis to modern-day conflicts. The Magisterium of the Church states that “unless there is a moral certainty of not causing harm,” experimentation on fetuses, fertilized cells, stem cells, or embryos constitutes a crime. [61] Such procedures would not respect the human person who exists at these stages, according to Catholicism. Damages to the embryo are considered gravely immoral and illicit. [62] Although the Catholic Church officially opposes abortion, surveys demonstrate that many Catholic people hold pro-choice views, whether due to the context of conception, stage of pregnancy, threat to the mother’s life, or for other reasons, demonstrating that practicing members can also accept some but not all tenets. [63]

Some major Jewish denominations, such as the Reform, Conservative, and Reconstructionist movements, are open to supporting ESC use or research as long as it is for saving a life. [64] Within Judaism, the Talmud, or study, gives personhood to the child at birth and emphasizes that life does not begin at conception: [65]

“If she is found pregnant, until the fortieth day it is mere fluid,” [66]

Whereas most religions prioritize the status of human embryos, the Halakah (Jewish religious law) states that to save one life, most other religious laws can be ignored because it is in pursuit of preservation. [67] Stem cell research is accepted due to application of these religious laws.

We recognize that all religions contain subsets and sects. The variety of environmental and cultural differences within religious groups requires further analysis to respect the flexibility of religious thoughts and practices. We make no presumptions that all cultures require notions of autonomy or morality as under the common morality theory , which asserts a set of universal moral norms that all individuals share provides moral reasoning and guides ethical decisions. [68] We only wish to show that the interaction with morality varies between cultures and countries.

III. A Flexible Ethical Approach

The plurality of different moral approaches described above demonstrates that there can be no universally acceptable uniform law for ESC on a global scale. Instead of developing one standard, flexible ethical applications must be continued. We recommend local guidelines that incorporate important cultural and ethical priorities.

While the Declaration of Helsinki is more relevant to people in clinical trials receiving ESC products, in keeping with the tradition of protections for research subjects, consent of the donor is an ethical requirement for ESC donation in many jurisdictions including the US, Canada, and Europe. [69] The Declaration of Helsinki provides a reference point for regulatory standards and could potentially be used as a universal baseline for obtaining consent prior to gamete or embryo donation.

For instance, in Columbia University’s egg donor program for stem cell research, donors followed standard screening protocols and “underwent counseling sessions that included information as to the purpose of oocyte donation for research, what the oocytes would be used for, the risks and benefits of donation, and process of oocyte stimulation” to ensure transparency for consent. [70] The program helped advance stem cell research and provided clear and safe research methods with paid participants. Though paid participation or covering costs of incidental expenses may not be socially acceptable in every culture or context, [71] and creating embryos for ESC research is illegal in many jurisdictions, Columbia’s program was effective because of the clear and honest communications with donors, IRBs, and related stakeholders. This example demonstrates that cultural acceptance of scientific research and of the idea that an egg or embryo does not have personhood is likely behind societal acceptance of donating eggs for ESC research. As noted, many countries do not permit the creation of embryos for research.

Proper communication and education regarding the process and purpose of stem cell research may bolster comprehension and garner more acceptance. “Given the sensitive subject material, a complete consent process can support voluntary participation through trust, understanding, and ethical norms from the cultures and morals participants value. This can be hard for researchers entering countries of different socioeconomic stability, with different languages and different societal values. [72]

An adequate moral foundation in medical ethics is derived from the cultural and religious basis that informs knowledge and actions. [73] Understanding local cultural and religious values and their impact on research could help researchers develop humility and promote inclusion.

IV. Concerns

Some may argue that if researchers all adhere to one ethics standard, protection will be satisfied across all borders, and the global public will trust researchers. However, defining what needs to be protected and how to define such research standards is very specific to the people to which standards are applied. We suggest that applying one uniform guide cannot accurately protect each individual because we all possess our own perceptions and interpretations of social values. [74] Therefore, the issue of not adjusting to the moral pluralism between peoples in applying one standard of ethics can be resolved by building out ethics models that can be adapted to different cultures and religions.

Other concerns include medical tourism, which may promote health inequities. [75] Some countries may develop and approve products derived from ESC research before others, compromising research ethics or drug approval processes. There are also concerns about the sale of unauthorized stem cell treatments, for example, those without FDA approval in the United States. Countries with robust research infrastructures may be tempted to attract medical tourists, and some customers will have false hopes based on aggressive publicity of unproven treatments. [76]

For example, in China, stem cell clinics can market to foreign clients who are not protected under the regulatory regimes. Companies employ a marketing strategy of “ethically friendly” therapies. Specifically, in the case of Beike, China’s leading stem cell tourism company and sprouting network, ethical oversight of administrators or health bureaus at one site has “the unintended consequence of shifting questionable activities to another node in Beike's diffuse network.” [77] In contrast, Jordan is aware of stem cell research’s potential abuse and its own status as a “health-care hub.” Jordan’s expanded regulations include preserving the interests of individuals in clinical trials and banning private companies from ESC research to preserve transparency and the integrity of research practices. [78]

The social priorities of the community are also a concern. The ISSCR explicitly states that guidelines “should be periodically revised to accommodate scientific advances, new challenges, and evolving social priorities.” [79] The adaptable ethics model extends this consideration further by addressing whether research is warranted given the varying degrees of socioeconomic conditions, political stability, and healthcare accessibilities and limitations. An ethical approach would require discussion about resource allocation and appropriate distribution of funds. [80]

While some religions emphasize the sanctity of life from conception, which may lead to public opposition to ESC research, others encourage ESC research due to its potential for healing and alleviating human pain. Many countries have special regulations that balance local views on embryonic personhood, the benefits of research as individual or societal goods, and the protection of human research subjects. To foster understanding and constructive dialogue, global policy frameworks should prioritize the protection of universal human rights, transparency, and informed consent. In addition to these foundational global policies, we recommend tailoring local guidelines to reflect the diverse cultural and religious perspectives of the populations they govern. Ethics models should be adapted to local populations to effectively establish research protections, growth, and possibilities of stem cell research.

For example, in countries with strong beliefs in the moral sanctity of embryos or heavy religious restrictions, an adaptive model can allow for discussion instead of immediate rejection. In countries with limited individual rights and voice in science policy, an adaptive model ensures cultural, moral, and religious views are taken into consideration, thereby building social inclusion. While this ethical consideration by the government may not give a complete voice to every individual, it will help balance policies and maintain the diverse perspectives of those it affects. Embracing an adaptive ethics model of ESC research promotes open-minded dialogue and respect for the importance of human belief and tradition. By actively engaging with cultural and religious values, researchers can better handle disagreements and promote ethical research practices that benefit each society.

This brief exploration of the religious and cultural differences that impact ESC research reveals the nuances of relative ethics and highlights a need for local policymakers to apply a more intense adaptive model.

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[3] International Society for Stem Cell Research. (2023). Laboratory-based human embryonic stem cell research, embryo research, and related research activities . International Society for Stem Cell Research. https://www.isscr.org/guidelines/blog-post-title-one-ed2td-6fcdk ; Kimmelman, J., Hyun, I., Benvenisty, N. et al. Policy: Global standards for stem-cell research. Nature 533 , 311–313 (2016). https://doi.org/10.1038/533311a

[4] International Society for Stem Cell Research. (2023). Laboratory-based human embryonic stem cell research, embryo research, and related research activities . International Society for Stem Cell Research. https://www.isscr.org/guidelines/blog-post-title-one-ed2td-6fcdk

[5] Concerning the moral philosophies of stem cell research, our paper does not posit a personal moral stance nor delve into the “when” of human life begins. To read further about the philosophical debate, consider the following sources:

Sandel M. J. (2004). Embryo ethics--the moral logic of stem-cell research. The New England journal of medicine , 351 (3), 207–209. https://doi.org/10.1056/NEJMp048145 ; George, R. P., & Lee, P. (2020, September 26). Acorns and Embryos . The New Atlantis. https://www.thenewatlantis.com/publications/acorns-and-embryos ; Sagan, A., & Singer, P. (2007). The moral status of stem cells. Metaphilosophy , 38 (2/3), 264–284. http://www.jstor.org/stable/24439776 ; McHugh P. R. (2004). Zygote and "clonote"--the ethical use of embryonic stem cells. The New England journal of medicine , 351 (3), 209–211. https://doi.org/10.1056/NEJMp048147 ; Kurjak, A., & Tripalo, A. (2004). The facts and doubts about beginning of the human life and personality. Bosnian journal of basic medical sciences , 4 (1), 5–14. https://doi.org/10.17305/bjbms.2004.3453

[6] Vazin, T., & Freed, W. J. (2010). Human embryonic stem cells: derivation, culture, and differentiation: a review. Restorative neurology and neuroscience , 28 (4), 589–603. https://doi.org/10.3233/RNN-2010-0543

[7] Socially, at its core, the Western approach to ethics is widely principle-based, autonomy being one of the key factors to ensure a fundamental respect for persons within research. For information regarding autonomy in research, see: Department of Health, Education, and Welfare, & National Commission for the Protection of Human Subjects of Biomedical and Behavioral Research (1978). The Belmont Report. Ethical principles and guidelines for the protection of human subjects of research.; For a more in-depth review of autonomy within the US, see: Beauchamp, T. L., & Childress, J. F. (1994). Principles of Biomedical Ethics . Oxford University Press.

[8] Sherley v. Sebelius , 644 F.3d 388 (D.C. Cir. 2011), citing 45 C.F.R. 46.204(b) and [42 U.S.C. § 289g(b)]. https://www.cadc.uscourts.gov/internet/opinions.nsf/6c690438a9b43dd685257a64004ebf99/$file/11-5241-1391178.pdf

[9] Stem Cell Research Enhancement Act of 2005, H. R. 810, 109 th Cong. (2001). https://www.govtrack.us/congress/bills/109/hr810/text ; Bush, G. W. (2006, July 19). Message to the House of Representatives . National Archives and Records Administration. https://georgewbush-whitehouse.archives.gov/news/releases/2006/07/20060719-5.html

[10] National Archives and Records Administration. (2009, March 9). Executive order 13505 -- removing barriers to responsible scientific research involving human stem cells . National Archives and Records Administration. https://obamawhitehouse.archives.gov/the-press-office/removing-barriers-responsible-scientific-research-involving-human-stem-cells

[11] Hurlbut, W. B. (2006). Science, Religion, and the Politics of Stem Cells. Social Research , 73 (3), 819–834. http://www.jstor.org/stable/40971854

[12] Akpa-Inyang, Francis & Chima, Sylvester. (2021). South African traditional values and beliefs regarding informed consent and limitations of the principle of respect for autonomy in African communities: a cross-cultural qualitative study. BMC Medical Ethics . 22. 10.1186/s12910-021-00678-4.

[13] Source for further reading: Tangwa G. B. (2007). Moral status of embryonic stem cells: perspective of an African villager. Bioethics , 21(8), 449–457. https://doi.org/10.1111/j.1467-8519.2007.00582.x , see also Mnisi, F. M. (2020). An African analysis based on ethics of Ubuntu - are human embryonic stem cell patents morally justifiable? African Insight , 49 (4).

[14] Jecker, N. S., & Atuire, C. (2021). Bioethics in Africa: A contextually enlightened analysis of three cases. Developing World Bioethics , 22 (2), 112–122. https://doi.org/10.1111/dewb.12324

[15] Jecker, N. S., & Atuire, C. (2021). Bioethics in Africa: A contextually enlightened analysis of three cases. Developing World Bioethics, 22(2), 112–122. https://doi.org/10.1111/dewb.12324

[16] Jackson, C.S., Pepper, M.S. Opportunities and barriers to establishing a cell therapy programme in South Africa. Stem Cell Res Ther 4 , 54 (2013). https://doi.org/10.1186/scrt204 ; Pew Research Center. (2014, May 1). Public health a major priority in African nations . Pew Research Center’s Global Attitudes Project. https://www.pewresearch.org/global/2014/05/01/public-health-a-major-priority-in-african-nations/

[17] Department of Health Republic of South Africa. (2021). Health Research Priorities (revised) for South Africa 2021-2024 . National Health Research Strategy. https://www.health.gov.za/wp-content/uploads/2022/05/National-Health-Research-Priorities-2021-2024.pdf

[18] Oosthuizen, H. (2013). Legal and Ethical Issues in Stem Cell Research in South Africa. In: Beran, R. (eds) Legal and Forensic Medicine. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-32338-6_80 , see also: Gaobotse G (2018) Stem Cell Research in Africa: Legislation and Challenges. J Regen Med 7:1. doi: 10.4172/2325-9620.1000142

[19] United States Bureau of Citizenship and Immigration Services. (1998). Tunisia: Information on the status of Christian conversions in Tunisia . UNHCR Web Archive. https://webarchive.archive.unhcr.org/20230522142618/https://www.refworld.org/docid/3df0be9a2.html

[20] Gaobotse, G. (2018) Stem Cell Research in Africa: Legislation and Challenges. J Regen Med 7:1. doi: 10.4172/2325-9620.1000142

[21] Kooli, C. Review of assisted reproduction techniques, laws, and regulations in Muslim countries. Middle East Fertil Soc J 24 , 8 (2020). https://doi.org/10.1186/s43043-019-0011-0 ; Gaobotse, G. (2018) Stem Cell Research in Africa: Legislation and Challenges. J Regen Med 7:1. doi: 10.4172/2325-9620.1000142

[22] Pang M. C. (1999). Protective truthfulness: the Chinese way of safeguarding patients in informed treatment decisions. Journal of medical ethics , 25(3), 247–253. https://doi.org/10.1136/jme.25.3.247

[23] Wang, L., Wang, F., & Zhang, W. (2021). Bioethics in China’s biosecurity law: Forms, effects, and unsettled issues. Journal of law and the biosciences , 8(1). https://doi.org/10.1093/jlb/lsab019 https://academic.oup.com/jlb/article/8/1/lsab019/6299199

[24] Wang, Y., Xue, Y., & Guo, H. D. (2022). Intervention effects of traditional Chinese medicine on stem cell therapy of myocardial infarction. Frontiers in pharmacology , 13 , 1013740. https://doi.org/10.3389/fphar.2022.1013740

[25] Li, X.-T., & Zhao, J. (2012). Chapter 4: An Approach to the Nature of Qi in TCM- Qi and Bioenergy. In Recent Advances in Theories and Practice of Chinese Medicine (p. 79). InTech.

[26] Luo, D., Xu, Z., Wang, Z., & Ran, W. (2021). China's Stem Cell Research and Knowledge Levels of Medical Practitioners and Students. Stem cells international , 2021 , 6667743. https://doi.org/10.1155/2021/6667743

[27] Luo, D., Xu, Z., Wang, Z., & Ran, W. (2021). China's Stem Cell Research and Knowledge Levels of Medical Practitioners and Students. Stem cells international , 2021 , 6667743. https://doi.org/10.1155/2021/6667743

[28] Zhang, J. Y. (2017). Lost in translation? accountability and governance of Clinical Stem Cell Research in China. Regenerative Medicine , 12 (6), 647–656. https://doi.org/10.2217/rme-2017-0035

[29] Wang, L., Wang, F., & Zhang, W. (2021). Bioethics in China’s biosecurity law: Forms, effects, and unsettled issues. Journal of law and the biosciences , 8(1). https://doi.org/10.1093/jlb/lsab019 https://academic.oup.com/jlb/article/8/1/lsab019/6299199

[30] Chen, H., Wei, T., Wang, H. et al. Association of China’s two-child policy with changes in number of births and birth defects rate, 2008–2017. BMC Public Health 22 , 434 (2022). https://doi.org/10.1186/s12889-022-12839-0

[31] Azuma, K. Regulatory Landscape of Regenerative Medicine in Japan. Curr Stem Cell Rep 1 , 118–128 (2015). https://doi.org/10.1007/s40778-015-0012-6

[32] Harris, R. (2005, May 19). Researchers Report Advance in Stem Cell Production . NPR. https://www.npr.org/2005/05/19/4658967/researchers-report-advance-in-stem-cell-production

[33] Park, S. (2012). South Korea steps up stem-cell work. Nature . https://doi.org/10.1038/nature.2012.10565

[34] Resnik, D. B., Shamoo, A. E., & Krimsky, S. (2006). Fraudulent human embryonic stem cell research in South Korea: lessons learned. Accountability in research , 13 (1), 101–109. https://doi.org/10.1080/08989620600634193 .

[35] Alahmad, G., Aljohani, S., & Najjar, M. F. (2020). Ethical challenges regarding the use of stem cells: interviews with researchers from Saudi Arabia. BMC medical ethics, 21(1), 35. https://doi.org/10.1186/s12910-020-00482-6

[36] Association for the Advancement of Blood and Biotherapies. https://www.aabb.org/regulatory-and-advocacy/regulatory-affairs/regulatory-for-cellular-therapies/international-competent-authorities/saudi-arabia

[37] Alahmad, G., Aljohani, S., & Najjar, M. F. (2020). Ethical challenges regarding the use of stem cells: Interviews with researchers from Saudi Arabia. BMC medical ethics , 21 (1), 35. https://doi.org/10.1186/s12910-020-00482-6

[38] Alahmad, G., Aljohani, S., & Najjar, M. F. (2020). Ethical challenges regarding the use of stem cells: Interviews with researchers from Saudi Arabia. BMC medical ethics , 21(1), 35. https://doi.org/10.1186/s12910-020-00482-6

Culturally, autonomy practices follow a relational autonomy approach based on a paternalistic deontological health care model. The adherence to strict international research policies and religious pillars within the regulatory environment is a great foundation for research ethics. However, there is a need to develop locally targeted ethics approaches for research (as called for in Alahmad, G., Aljohani, S., & Najjar, M. F. (2020). Ethical challenges regarding the use of stem cells: interviews with researchers from Saudi Arabia. BMC medical ethics, 21(1), 35. https://doi.org/10.1186/s12910-020-00482-6), this decision-making approach may help advise a research decision model. For more on the clinical cultural autonomy approaches, see: Alabdullah, Y. Y., Alzaid, E., Alsaad, S., Alamri, T., Alolayan, S. W., Bah, S., & Aljoudi, A. S. (2022). Autonomy and paternalism in Shared decision‐making in a Saudi Arabian tertiary hospital: A cross‐sectional study. Developing World Bioethics , 23 (3), 260–268. https://doi.org/10.1111/dewb.12355 ; Bukhari, A. A. (2017). Universal Principles of Bioethics and Patient Rights in Saudi Arabia (Doctoral dissertation, Duquesne University). https://dsc.duq.edu/etd/124; Ladha, S., Nakshawani, S. A., Alzaidy, A., & Tarab, B. (2023, October 26). Islam and Bioethics: What We All Need to Know . Columbia University School of Professional Studies. https://sps.columbia.edu/events/islam-and-bioethics-what-we-all-need-know

[39] Ababneh, M. A., Al-Azzam, S. I., Alzoubi, K., Rababa’h, A., & Al Demour, S. (2021). Understanding and attitudes of the Jordanian public about clinical research ethics. Research Ethics , 17 (2), 228-241. https://doi.org/10.1177/1747016120966779

[40] Ababneh, M. A., Al-Azzam, S. I., Alzoubi, K., Rababa’h, A., & Al Demour, S. (2021). Understanding and attitudes of the Jordanian public about clinical research ethics. Research Ethics , 17 (2), 228-241. https://doi.org/10.1177/1747016120966779

[41] Dajani, R. (2014). Jordan’s stem-cell law can guide the Middle East. Nature 510, 189. https://doi.org/10.1038/510189a

[42] Dajani, R. (2014). Jordan’s stem-cell law can guide the Middle East. Nature 510, 189. https://doi.org/10.1038/510189a

[43] The EU’s definition of autonomy relates to the capacity for creating ideas, moral insight, decisions, and actions without constraint, personal responsibility, and informed consent. However, the EU views autonomy as not completely able to protect individuals and depends on other principles, such as dignity, which “expresses the intrinsic worth and fundamental equality of all human beings.” Rendtorff, J.D., Kemp, P. (2019). Four Ethical Principles in European Bioethics and Biolaw: Autonomy, Dignity, Integrity and Vulnerability. In: Valdés, E., Lecaros, J. (eds) Biolaw and Policy in the Twenty-First Century. International Library of Ethics, Law, and the New Medicine, vol 78. Springer, Cham. https://doi.org/10.1007/978-3-030-05903-3_3

[44] Council of Europe. Convention for the protection of Human Rights and Dignity of the Human Being with regard to the Application of Biology and Medicine: Convention on Human Rights and Biomedicine (ETS No. 164) https://www.coe.int/en/web/conventions/full-list?module=treaty-detail&treatynum=164 (forbidding the creation of embryos for research purposes only, and suggests embryos in vitro have protections.); Also see Drabiak-Syed B. K. (2013). New President, New Human Embryonic Stem Cell Research Policy: Comparative International Perspectives and Embryonic Stem Cell Research Laws in France. Biotechnology Law Report , 32 (6), 349–356. https://doi.org/10.1089/blr.2013.9865

[45] Rendtorff, J.D., Kemp, P. (2019). Four Ethical Principles in European Bioethics and Biolaw: Autonomy, Dignity, Integrity and Vulnerability. In: Valdés, E., Lecaros, J. (eds) Biolaw and Policy in the Twenty-First Century. International Library of Ethics, Law, and the New Medicine, vol 78. Springer, Cham. https://doi.org/10.1007/978-3-030-05903-3_3

[46] Tomuschat, C., Currie, D. P., Kommers, D. P., & Kerr, R. (Trans.). (1949, May 23). Basic law for the Federal Republic of Germany. https://www.btg-bestellservice.de/pdf/80201000.pdf

[47] Regulation of Stem Cell Research in Germany . Eurostemcell. (2017, April 26). https://www.eurostemcell.org/regulation-stem-cell-research-germany

[48] Regulation of Stem Cell Research in Finland . Eurostemcell. (2017, April 26). https://www.eurostemcell.org/regulation-stem-cell-research-finland

[49] Regulation of Stem Cell Research in Spain . Eurostemcell. (2017, April 26). https://www.eurostemcell.org/regulation-stem-cell-research-spain

[50] Some sources to consider regarding ethics models or regulatory oversights of other cultures not covered:

Kara MA. Applicability of the principle of respect for autonomy: the perspective of Turkey. J Med Ethics. 2007 Nov;33(11):627-30. doi: 10.1136/jme.2006.017400. PMID: 17971462; PMCID: PMC2598110.

Ugarte, O. N., & Acioly, M. A. (2014). The principle of autonomy in Brazil: one needs to discuss it ... Revista do Colegio Brasileiro de Cirurgioes , 41 (5), 374–377. https://doi.org/10.1590/0100-69912014005013

Bharadwaj, A., & Glasner, P. E. (2012). Local cells, global science: The rise of embryonic stem cell research in India . Routledge.

For further research on specific European countries regarding ethical and regulatory framework, we recommend this database: Regulation of Stem Cell Research in Europe . Eurostemcell. (2017, April 26). https://www.eurostemcell.org/regulation-stem-cell-research-europe

[51] Klitzman, R. (2006). Complications of culture in obtaining informed consent. The American Journal of Bioethics, 6(1), 20–21. https://doi.org/10.1080/15265160500394671 see also: Ekmekci, P. E., & Arda, B. (2017). Interculturalism and Informed Consent: Respecting Cultural Differences without Breaching Human Rights. Cultura (Iasi, Romania) , 14 (2), 159–172.; For why trust is important in research, see also: Gray, B., Hilder, J., Macdonald, L., Tester, R., Dowell, A., & Stubbe, M. (2017). Are research ethics guidelines culturally competent? Research Ethics , 13 (1), 23-41. https://doi.org/10.1177/1747016116650235

[52] The Qur'an (M. Khattab, Trans.). (1965). Al-Mu’minun, 23: 12-14. https://quran.com/23

[53] Lenfest, Y. (2017, December 8). Islam and the beginning of human life . Bill of Health. https://blog.petrieflom.law.harvard.edu/2017/12/08/islam-and-the-beginning-of-human-life/

[54] Aksoy, S. (2005). Making regulations and drawing up legislation in Islamic countries under conditions of uncertainty, with special reference to embryonic stem cell research. Journal of Medical Ethics , 31: 399-403.; see also: Mahmoud, Azza. "Islamic Bioethics: National Regulations and Guidelines of Human Stem Cell Research in the Muslim World." Master's thesis, Chapman University, 2022. https://doi.org/10.36837/ chapman.000386

[55] Rashid, R. (2022). When does Ensoulment occur in the Human Foetus. Journal of the British Islamic Medical Association , 12 (4). ISSN 2634 8071. https://www.jbima.com/wp-content/uploads/2023/01/2-Ethics-3_-Ensoulment_Rafaqat.pdf.

[56] Sivaraman, M. & Noor, S. (2017). Ethics of embryonic stem cell research according to Buddhist, Hindu, Catholic, and Islamic religions: perspective from Malaysia. Asian Biomedicine,8(1) 43-52. https://doi.org/10.5372/1905-7415.0801.260

[57] Jafari, M., Elahi, F., Ozyurt, S. & Wrigley, T. (2007). 4. Religious Perspectives on Embryonic Stem Cell Research. In K. Monroe, R. Miller & J. Tobis (Ed.), Fundamentals of the Stem Cell Debate: The Scientific, Religious, Ethical, and Political Issues (pp. 79-94). Berkeley: University of California Press. https://escholarship.org/content/qt9rj0k7s3/qt9rj0k7s3_noSplash_f9aca2e02c3777c7fb76ea768ba458f0.pdf https://doi.org/10.1525/9780520940994-005

[58] Lecso, P. A. (1991). The Bodhisattva Ideal and Organ Transplantation. Journal of Religion and Health , 30 (1), 35–41. http://www.jstor.org/stable/27510629 ; Bodhisattva, S. (n.d.). The Key of Becoming a Bodhisattva . A Guide to the Bodhisattva Way of Life. http://www.buddhism.org/Sutras/2/BodhisattvaWay.htm

[59] There is no explicit religious reference to when life begins or how to conduct research that interacts with the concept of life. However, these are relevant verses pertaining to how the fetus is viewed. (( King James Bible . (1999). Oxford University Press. (original work published 1769))

Jerimiah 1: 5 “Before I formed thee in the belly I knew thee; and before thou camest forth out of the womb I sanctified thee…”

In prophet Jerimiah’s insight, God set him apart as a person known before childbirth, a theme carried within the Psalm of David.

Psalm 139: 13-14 “…Thou hast covered me in my mother's womb. I will praise thee; for I am fearfully and wonderfully made…”

These verses demonstrate David’s respect for God as an entity that would know of all man’s thoughts and doings even before birth.

[60] It should be noted that abortion is not supported as well.

[61] The Vatican. (1987, February 22). Instruction on Respect for Human Life in Its Origin and on the Dignity of Procreation Replies to Certain Questions of the Day . Congregation For the Doctrine of the Faith. https://www.vatican.va/roman_curia/congregations/cfaith/documents/rc_con_cfaith_doc_19870222_respect-for-human-life_en.html

[62] The Vatican. (2000, August 25). Declaration On the Production and the Scientific and Therapeutic Use of Human Embryonic Stem Cells . Pontifical Academy for Life. https://www.vatican.va/roman_curia/pontifical_academies/acdlife/documents/rc_pa_acdlife_doc_20000824_cellule-staminali_en.html ; Ohara, N. (2003). Ethical Consideration of Experimentation Using Living Human Embryos: The Catholic Church’s Position on Human Embryonic Stem Cell Research and Human Cloning. Department of Obstetrics and Gynecology . Retrieved from https://article.imrpress.com/journal/CEOG/30/2-3/pii/2003018/77-81.pdf.

[63] Smith, G. A. (2022, May 23). Like Americans overall, Catholics vary in their abortion views, with regular mass attenders most opposed . Pew Research Center. https://www.pewresearch.org/short-reads/2022/05/23/like-americans-overall-catholics-vary-in-their-abortion-views-with-regular-mass-attenders-most-opposed/

[64] Rosner, F., & Reichman, E. (2002). Embryonic stem cell research in Jewish law. Journal of halacha and contemporary society , (43), 49–68.; Jafari, M., Elahi, F., Ozyurt, S. & Wrigley, T. (2007). 4. Religious Perspectives on Embryonic Stem Cell Research. In K. Monroe, R. Miller & J. Tobis (Ed.), Fundamentals of the Stem Cell Debate: The Scientific, Religious, Ethical, and Political Issues (pp. 79-94). Berkeley: University of California Press. https://escholarship.org/content/qt9rj0k7s3/qt9rj0k7s3_noSplash_f9aca2e02c3777c7fb76ea768ba458f0.pdf https://doi.org/10.1525/9780520940994-005

[65] Schenker J. G. (2008). The beginning of human life: status of embryo. Perspectives in Halakha (Jewish Religious Law). Journal of assisted reproduction and genetics , 25 (6), 271–276. https://doi.org/10.1007/s10815-008-9221-6

[66] Ruttenberg, D. (2020, May 5). The Torah of Abortion Justice (annotated source sheet) . Sefaria. https://www.sefaria.org/sheets/234926.7?lang=bi&with=all&lang2=en

[67] Jafari, M., Elahi, F., Ozyurt, S. & Wrigley, T. (2007). 4. Religious Perspectives on Embryonic Stem Cell Research. In K. Monroe, R. Miller & J. Tobis (Ed.), Fundamentals of the Stem Cell Debate: The Scientific, Religious, Ethical, and Political Issues (pp. 79-94). Berkeley: University of California Press. https://escholarship.org/content/qt9rj0k7s3/qt9rj0k7s3_noSplash_f9aca2e02c3777c7fb76ea768ba458f0.pdf https://doi.org/10.1525/9780520940994-005

[68] Gert, B. (2007). Common morality: Deciding what to do . Oxford Univ. Press.

[69] World Medical Association (2013). World Medical Association Declaration of Helsinki: ethical principles for medical research involving human subjects. JAMA , 310(20), 2191–2194. https://doi.org/10.1001/jama.2013.281053 Declaration of Helsinki – WMA – The World Medical Association .; see also: National Commission for the Protection of Human Subjects of Biomedical and Behavioral Research. (1979). The Belmont report: Ethical principles and guidelines for the protection of human subjects of research . U.S. Department of Health and Human Services. https://www.hhs.gov/ohrp/regulations-and-policy/belmont-report/read-the-belmont-report/index.html

[70] Zakarin Safier, L., Gumer, A., Kline, M., Egli, D., & Sauer, M. V. (2018). Compensating human subjects providing oocytes for stem cell research: 9-year experience and outcomes. Journal of assisted reproduction and genetics , 35 (7), 1219–1225. https://doi.org/10.1007/s10815-018-1171-z https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6063839/ see also: Riordan, N. H., & Paz Rodríguez, J. (2021). Addressing concerns regarding associated costs, transparency, and integrity of research in recent stem cell trial. Stem Cells Translational Medicine , 10 (12), 1715–1716. https://doi.org/10.1002/sctm.21-0234

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[76] Stem Cell Tourism: False Hope for Real Money . Harvard Stem Cell Institute (HSCI). (2023). https://hsci.harvard.edu/stem-cell-tourism , See also: Bissassar, M. (2017). Transnational Stem Cell Tourism: An ethical analysis. Voices in Bioethics , 3 . https://doi.org/10.7916/vib.v3i.6027

[77] Song, P. (2011) The proliferation of stem cell therapies in post-Mao China: problematizing ethical regulation, New Genetics and Society , 30:2, 141-153, DOI: 10.1080/14636778.2011.574375

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Olivia Bowers

MS Bioethics Columbia University (Disclosure: affiliated with Voices in Bioethics)

Mifrah Hayath

SM Candidate Harvard Medical School, MS Biotechnology Johns Hopkins University

Article Details

This work is licensed under a Creative Commons Attribution 4.0 International License .

Social Representativeness and Intervention Adherence—A Systematic Review of Clinical Physical Activity Trials in Breast Cancer Patients

1 Department of Circulation and Medical Imaging, Norwegian University of Technology and Science (NTNU), Trondheim, Norway
2 Department of Neuromedicine and Movement Science, Norwegian University of Technology and Science (NTNU), Trondheim, Norway

Objectives: Representativeness in physical activity randomised controlled trials (RCT) in breast cancer patients is essential to analyses of feasibility and validity considering privileged- social groups. A step-by-step exclusion of less privileged groups through the trial process could reinforce health inequality. This study aimed at examining representativeness in breast cancer (BC) physical activity trials, investigate associations between socio-economic status (SES) and intervention adherence, and explore associations between representativeness and the relationship between SES and intervention adherence.

Methods: Systematic, computerised searches were performed in PubMed, CINAHL, AMED, EMBASE and PsycINFO. Additional citation-based searches retrieved 37 articles. Distributions of education level, ethnicity, and marital status in study samples were compared to national populations data to estimate representativeness in less privileged groups.

Results: A preponderance of studies favoured educated, married and white patients. Only six studies reported SES-adherence associations, hampering conclusions on this relationship and possible associations between representativeness and an SES-adherence relationship.

Conclusion: Less educated, unmarried and non-white individuals may be underrepresented in BC physical activity RCTs, while SES-adherence associations in such trials are inconclusive. Unintentional social misrepresentations may indicate that disguised inequity warrants revived attention.

Introduction

Clinical trials in breast cancer (BC) research have contributed significantly to improved treatments, health-related quality of life, and survival probability for BC patients [ 1 ]. For example, numerous clinical physical activity (PA) trials have been conducted. Nevertheless, faced with the reality of social health inequalities [ 2 , 3 ], it is essential to ensure that the results of these trials benefit all, not exclusively the most privileged. Previous analyses have concluded that study samples only slightly represent real-world patient populations [ 4 ] due to participants having better health status, lower age, and a dominant ethnicity. However, research inequity on the part of socioeconomic status (SES)-groups has been scarcely investigated. As PA appears to improve physical fitness [ 5 – 8 ], fatigue [ 5 , 6 , 9 , 10 ], and physical functioning [ 5 , 9 , 11 ] in BC patients and survivors, knowledge about representativeness across SES and privilege in randomised controlled trials (RCT) with PA is warranted.

Privilege refers to (often unrecognised) advantages that benefit people belonging to certain groups based on factors like their SES, ethnicity, age, gender identity [ 12 ]. High-SES individuals, for example, are considered to have health benefits as a result of their belonging to a privileged social group [ 13 ]. SES, is ideally measured as the combination of an individual’s or groups’ education, income and occupation [ 14 ] and it is often used to examine social health inequalities [ 15 ]. In the case of BC, there is an excess risk associated with increased education, in both men [ 16 ] and women [ 17 ]. Unmarried women, who face a multitude of hardships and less privilege [ 18 ], may have a higher risk of developing BC [ 19 ]. Similarly, less privileged non-whites have higher odds of being diagnosed with aggressive BC [ 20 ]. However, BC in men and less privileged women is generally diagnosed later, making these cases more severe compared to BC diagnosed in privileged women [ 21 ]. Despite higher incidence rates of early BC, higher survival rates and better health-related quality of life after diagnosis [ 22 ] are associated with higher education [ 23 ]. In young men with invasive BC, overall survival is found to decrease in groups living in ZIP-code areas associated with low SES [ 24 ]. Presumably because <1% of all BC incidents occur in men [ 25 ], most PA research concern women. Female patients often report weight gain, which is associated with undesirable BC-outcomes [ 26 – 28 ]. Thus, it is often recommended that they pursue regular PA [ 29 ]. An inactive lifestyle is suggested to be a significant social determinant of decreased BC survival probability in low-SES groups [ 30 ], and according to Boer et al., there is strong evidence that BC recurrence and mortality are strongly associated with leisure-time PA (LTPA) due to the biological mechanisms affected [ 31 ].

PA is defined as any bodily movement produced by skeletal muscles that results in energy expenditure [ 32 ] and includes the active transport-, leisure time- (including exercise), job-related-, and household PA domains [ 33 ]. The relationship between PA and the risk of BC is well documented [ 34 – 44 ] and is evident for LTPA in postmenopausal BC [ 45 , 46 ]. However, it has been found that different SES-groups in general are inclined to different domains of PA, with high-SES groups being more physically active within the LTPA domain [ 47 ]. Comparable results are reported in studies of women with BC [ 48 – 51 ]. Hence, for RCTs with LTPA, there is a risk of selection bias, which is also acknowledged in the Exercise guidelines for cancer survivors: “ …the individuals enrolled in studies commonly meet prespecified eligibility criteria (…) and were willing to take part in research. This often results in a sample that is healthier or with higher physical function and exercise motivation that may not fully generalize to the broader population of cancer survivors. ” [ 52 ].

Moreover, if there are SES-differences in PA among women with BC in general, participation and adherence to PA trials may differ accordingly. Studies have shown different PA barriers across SES [ 53 , 54 ], partly explaining variances in activity levels [ 55 – 59 ]. If low-SES individuals perform less LTPA than high-SES individuals [ 47 ], the former may be prone to lower participation and adherence rates in exercise RCTs. In addition to findings of better exercise trial adherence in high-SES groups [ 60 , 61 ], less privileged individuals less frequently volunteer to participate in research [ 62 , 63 ], due to barriers to access [ 62 ], lower health literacy and negative attitudes towards research, additional costs, or disease status [ 64 ]. These findings may imply that RCTs with which a privileged group is more familiar and motivated for the provided intervention (i.e., LTPA/exercise) run higher risks of selection bias than RCTs for which compliance is less affected by social grouping.

Hence, the external validity of LTPA trials for BC patients may be impaired, albeit unintendedly, by a stepwise exclusion of less privileged patients; they appear to be recruited and participate less frequently, and may also have lower adherence rates [ 65 ]. The general view is that RCT samples must be homogeneous to gain internal validity and reliable results [ 66 , 67 ]. Simultaneously, the declarations of Helsinki [ 68 ], legitimately and necessarily, prevents researchers from obliging participation for the purpose of representativeness. Consequently, social biases may be fortified [ 64 , 65 ].

The credibility and success of medical progress depend on transparent reporting [ 69 ]. Thus, the CONSORT guidelines developed to improve RCT-articles [ 70 ]. Nevertheless, participant attributes, such as SES-indicators, are seldomly reported [ 71 , 72 ], impeding successful assessments of equitable research [ 72 ]. A reasonable alternative may be to employ the available variables that indicate, or strongly correlate with, privilege and SES. Previous reviews of PA-SES associations have found that education is the most reported SES-indicator [ 47 , 73 , 74 ]. Furthermore, frequently reported characteristics, such as ethnicity and marital status, both reflect social privilege and correlate with SES, thus they may be considered fair representations of privilege in the absence of precise SES-indicators.

The objective of this systematic review was to study previous PA RCTs on BC patients with the intention of examining a) SES-related information and representativeness, b) associations between SES-related indicators and PA intervention adherence, and c) associations between representativeness and reported relationships between SES and intervention adherences. There are, of course, real obstacles to recruting less privileged patients, so non-representative samples should not be seen as researchers’ unwillingness or lack of effort to include the less privileged. The overall aim of the study was not to evaluate single studies conducted for purposes other than representativeness per se , but rather to highlight disguised patterns across comparable studies [ 75 ]. Furthermore, the aim was not to provide meta-analyses and precise sample- vs real-world ratios; however, the study may render a departure point for improving representativeness on the part of less privileged groups.

Systematic, computerised searches were conducted in the PubMed, CINAHL, AMED, EMBASE and PsycINFO databases. The first round followed a traditional method [ 76 ]; we specified a search query by a set and combinations of words, and all publications indexed in the databases that contained those words were returned. “Compliance,” “persistence,” “fidelity,” “maintenance” and “concordance” were used as synonyms for the variable “adherence.” Similarly, “physical,” “exercise,” “fitness,” “sport” and “training” were used as synonyms, in addition to exercise-specific terms, such as “dance,” “swim,” “walk” and “yoga,” to cover any type of PA intervention. An asterisk (*) was attached to the roots of the words to broaden the search, and to retrieve variations on these terms. Because the terms are used interchangeably in the literature, both “ patients ” and “ survivors ” were used to cover relevant study samples. As recommended by Bramer et al. [ 77 ]. Boolean combinations were used to construct suitable search queries in combination with the basic term “breast cancer” (see Figure 1 ). There were no search limits as to publication year.

Figure 1 . Flow chart of inclusion and exclusion of articles through descriptive- and citation-based searches (Global, 2000–2020).

The following criteria guided the inclusion and exclusion process, defining the final dataset:

Inclusion Criteria

a) Empirical studies

b) …reporting RCTs including a PA intervention.

c) …including individuals undergoing BC treatment within one-year postdiagnosis.

d) …reporting adherence to the PA intervention.

e) …presenting a comprehensible calculation of adherence.

f) …written in English.

Exclusion Criteria

a) Reviews, theoretical and descriptive papers, books, theses, letters to editor or editorials.

b) …reporting on multiple cancer diagnoses (even if BC was included).

c) …not reporting any SES-related characteristics of the sample … written in any non-English language.

The descriptive searches retrieved 1,019 articles. After excluding immediate duplicates, 766 articles were manually examined and deemed potentially relevant based on a screening of titles and abstracts. This left, 166 potentially relevant articles that were examined to establish their eligibility according to the criteria. An algorithm for all variables was implemented using Python3 to ensure the eligibility of the articles selected. In total, 143 articles were excluded for a total of 23 remaining articles ( Figure 1 ).

To retrieve all possible relevant studies, thus reducing the risk of missing information [ 78 ], citation-based searches (described by Hu et al. [ 79 ], but implemented in Rysstad and Pedersen [ 80 ] and Darvik et al. [ 81 ]) were performed based on the 23 articles found in the descriptive searches. A forward citation-based (FCB) search of articles that cited the articles included in the descriptive searches was first reviewed for eligibility, and 34 potentially relevant articles were identified, 24 of which were excluded. A backwards citation-based (BCB) search, where the reference lists in the 33 articles already included in the material were scanned for eligible studies, retrieved 5 articles of which one replaced a previously included article, following the inclusion criteria.

In cases in which an article reported on two different parent trials, the article was included on the condition that at least one of the parent studies met inclusion criteria c. If two articles were reporting on the same parent RCT sample and overlapped in their data, the earliest article was included. If, however, only one of them reported adherence rates, the article omitting adherence rates was excluded. Nevertheless, the included article had to report on SES-related patient characteristics. In the subsequent step of the inclusion/exclusion process, only articles reporting the samples’ SES distributions were included for further analyses.

The second author performed the database searches but conferred with the first author to discuss any cases of doubt about the potentially relevant articles returned from the query.

Data Extraction and Analysis

The following variables were extracted from the articles: sample descriptions, intervention designs, aims of the studies, measures of SES or privilege, their distributions, and adherence calculations and -rates. For studies that investigated the associations between adherence and SES-related factors, the reported results were registered.

The SES-related distribution in the sample was compared with the corresponding distribution within the country in which the study was conducted, at the matching time of publication. Because adherence to intervention protocols was embedded in our study objectives, only intervention group characteristics were analysed. Due to third-party researchers’ limited access to patient population data, SES-related distribution in a country population, in the corresponding age groups, was used as a proxy for the patient population. For the education variable, the percentage of the study sample holding any tertiary education (no degree required) was compared with the percentage of the country population holding the same educational level (i.e., all formal postsecondary education, including public and private universities, colleges, technical training institutes, and vocational schools [ 82 ]), using public statistics for reference [ 83 – 86 ] (see Supplementary Files S2, S3 for details). Because the final data set included articles about women exclusively, all statistics retrieved and analysed, were relevant to women.

Similarly, the proportion of married women in the study samples and in the associated country populations was compared using United Nations World Marriage Data (age 45–49) [ 87 ] and a corresponding analysis for ethnicity based on national censuses [ 88 – 92 ]. Frequencies in the white alone and non-indigenous and non-visible minority categories from accessible censuses were used to estimate figures for intercensal years by interpolation. The relative differences between the study samples and the associated countries were calculated as follows:

Studies reporting on the association between SES-related factors and adherence to the PA intervention were further explored, and variations in adherence calculations were examined.

The preliminary screening excluded 20%–25% of all potentially relevant articles due to a lack of information about SES-related characteristics. The subsequent selection process, following descriptive, FBC- and BCB-searches, retrieved 37 eligible articles ( Figure 1 ).

A total of 28 (76%) of the included studies were published between 2010 and 2020, and the oldest article was published in 2002 [ 93 ]. Most studies (81%) were conducted in Western countries: 18 in the United States, 5 in Canada, two in the Netherlands, and one each in Spain, France, the United Kingdom, Denmark and Sweden. Six (16%) studies were Asian, including one Indian, two Chinese and three Taiwanese studies. In addition, one Brazilian study was included. The (full) sample sizes ranged from 14 [ 94 ] to 301 [ 95 ], including 11 studies with <50 participants, 15 studies with 50–96 participants, and 11 studies with 100–301 participants. The mean age ranged from 42.1 to 63.2 years (total mean = 51 years) ( Table 1 ). All included studies were of female BC patients.

Table 1 . Study aim, sample, SES and intervention descriptions, adherence formula, and adherence outcome in included studies. (Global, 2000–2020).

Education was the most frequently used indicator of privilege and was found in 30 (81%) of the articles [ 93 – 122 ] ( Table 1 ). Marital status was reported in 28 (76%) [ 93 – 95 , 97 – 99 , 101 – 109 , 111 – 115 , 122 ], ethnicity in 22 articles (59%) [ 93 – 95 , 102 , 105 , 108 , 110 , 112 , 114 – 116 , 119 , 123 – 128 ] employment status in 25 articles (68%) [ 93 – 95 , 98 , 101 , 102 , 104 , 106 – 111 , 113 – 115 , 118 , 119 ], and income in eight articles (22%) [ 95 , 96 , 103 , 104 , 114 , 116 , 122 , 123 ]. Two articles [ 95 , 114 ] reported five indicators, and four [ 124 , 126 , 127 , 129 ] reported one. Ethnicity was reported in all 18 USA studies, as well as in four of the five Canadian studies, but it was not reported in the remaining studies. For the rest of the indicators, no geographical patterns were identified.

There was no uniform definition of adherence although the most common calculation was attendance rates relative to total, or weekly, prescribed, or possible, PA sessions. The mean adherence rate for these studies was 78.9% (30.4%–100%). All studies reported on patients diagnosed with BC in stages 0–III.*. Most studies reported the feasibility or effect of a PA intervention on patients undergoing radiation-, chemotherapy, or both.

The PA-interventions were designed differently in terms of PA type (e.g., walking, exercise including endurance and strength, yoga, aerobics, martial arts, dancing, cycling, qigong, balance training, Pilates), intensity (e.g., according to Ainsworth et al. [ 130 ], yoga is performed at 2.5 METs, whereas bicycling could require 4–16 METs), duration (10–60 min/session, 6 weeks–12 months/intervention) and frequency (voluntarily–5 bouts/week).

Privileged Groups and Adherence to PA Interventions

Some articles were feasibility studies centred on adherence; others reported adherence as a sub-analysis. Six studies reported on the relationship between SES-related factors and adherence to or completion of the intervention [ 97 , 104 , 107 , 109 , 111 , 114 ]. However, two of these studies reported no significant difference in participant characteristics between withdrawers and completers [ 111 ] or between those with 75% attendance and other participants [ 114 ], without specified SES-indicators. Three of these six studies indicated a positive, however weak, association between adherence to an aerobic- and strength training protocol and educational level [ 97 , 104 , 109 ]. One study [ 107 ] noted that employment status was associated with adherence measured as intensity, but not when adherence was assessed in terms of exercise time. No differences in adherence across educational levels were reported in this study.

Representativeness in terms of Research Participants’ Education, Ethnicity and Marital Status

Figure 2 displays the sample-country differences in educational level. Eight studies had a lower proportion of individuals with higher education compared to the country population [ 97 – 99 , 101 , 106 , 107 , 114 , 121 ], whereas 21 studies showed the opposite trend. In 11 of these studies, the proportion of participants who had tertiary education in the population was >25% lower compared to the sample [ 94 , 96 , 100 , 102 – 105 , 109 , 111 , 120 , 122 ]. Four studies had a difference ≤10% [ 93 , 95 , 108 , 115 ] ( Figure 2 ; Table 1 in Supplementary Files S1–S3 ).

Figure 2 . Relative differences (%) between study samples and country populations considering either mean years of education (*) or % of women with >1 year of high education in study sample. Bars extending the right side indicate studies with high-education group overrepresentation (Global, 2000–2020).

The mean proportion of married women in the relevant samples was 71.9% (SD = 11.68), while the corresponding number was 73.9 (SD = 7.32) for the country populations ( Figure 3 ; Table 2 in Supplementary File S1 ). Sixteen of the studies using marital status reported their results on samples with a lower proportion of married women compared to the country population [ 93 , 95 , 97 , 98 , 103 , 104 , 107 , 108 , 111 – 115 , 121 , 122 , 125 ], while 11 examined samples with a higher proportion of married women compared to the country population [ 94 , 99 , 101 , 102 , 106 , 109 , 117 – 119 , 123 , 131 ]. One study [ 105 ] showed no difference (Tables 2, 3 in Supplementary File S1 ).

Figure 3 . (A) Study origin, publication year, and proportion (%) of married and non-married women in sample (left) and country (right). (B) Study origin, publication year, and proportion (%) of whites and other ethnicities in sample (left) and country (right) (Global, 2000–2020).

In the 22 studies that reported ethnicity , the mean proportion of whites was 81%: 77.6% Canadian studies, and 81.8% American studies ( Figure 3 ; Table 3 in Supplementary File S1 ). Three of these studies reported their results on samples with a lower proportion of whites compared with the country population, while the remaining 19 studies had samples with a higher proportion of whites. There was a difference between samples and countries of 10%–25% in 15 of these studies (Table 3 in Supplementary File S1 ).

Representativeness and Adherence

There was no clear relationship between the registered representativeness and the associations between indicators of SES and adherence. Three of the six mentioned studies reporting such associations [ 97 , 107 , 114 ] had samples with a lower proportion of high-SES BC patients compared to their country populations, while the other three [ 104 , 109 , 111 ] had samples with a higher proportion of high-SES patients.

To our knowledge, this is the first systematic review to report the social representativeness of RCTs examining the effects of PA on BC-related outcomes. In the included dataset, there was a preponderance of studies overrepresenting groups associated with higher privilege, supporting previous results indicating social bias [ 132 ]. Misrepresentations were found across different indicators of privilege, likely because different indicators tend to interrelate [ 133 ]. Our findings coincide with earlier observations that low-SES patients are less inclined to participate in research than high-SES patients [ 62 , 63 ], as well as with previous findings of obstacles to recruiting less privileged populations to cancer RCTs [ 64 ].

The most pronounced findings were based on studies that reported participants’ education. However, in six studies that did not record education but rather recorded ethnicity/race, as in the total dataset, there was a preponderance of white participants. In agreement with previous reports [ 62 , 132 , 134 ], this was interpreted as recruitment bias, although these analyses were based on less accurate data compared to the analyses on education. All 22 studies reporting ethnicity were from the USA and Canada, where the ethnic distribution varies over time and space, particularly in the United States [ 91 ]. Although education and income relate to ethnicity [ 135 ], our results on the representativeness of ethnic groups are unclear due to inaccurate data and increased confusion among the populations regarding ethnic categories. In general, it may appear inappropriate to use the category white as an exclusive indicator of social privilege in global comparative analyses such as the current study. Nonetheless, in the overall discussion of representativeness in RCTs, research favouring certain ethnicities over others should not be supported.

Representativeness was further assessed by marital status, and the mean difference between the study samples and the associated country populations was small. However, the differences ranged from −78% to 17.7%, and only 9 studies differed less than 5% from the country population. This means that although marital status is considered a measure of whether people have the social and financial benefits of being coupled, it could affect the possibility of being included in a PA trial.

What is considered an acceptable level of representativeness in RCT samples is difficult to decide. Recruitment issues may lead to sample biases, as patient populations often differ across social groups due to their diagnoses or hospital characteristics. However, the body of articles from the current dataset that employed education as the SES-indicator included eight studies with ( “negative” differences from the country population and 22 studies with “positive” differences (including 11 samples with >25% difference from the country population), which are significant findings. The fact that studies with a negative deviation from the country’s corresponding distribution in this subgroup were published after 2015 could be an effect of the CONSORT guidelines [ 70 ] and the Belmont report [ 136 ], which emphasised the implications of selection biases. However, our screening and analyses clearly show that there is still a potential for improvement among researchers in their attention to social distribution in samples.

Our results may have been more valid if baseline characteristics were compared with a real-world patient population and a patient sample (see [ 4 ]). However, such analyses require that third-party researchers also have access to exact data about the patient populations within each region, at the precise time of the studies, in addition to which patients are eligible according to each of the RCT criteria. The primary aim of the present study was to revive the question of external validity and feasibility from a perspective of social health inequalities in PA research. Therefore, status distribution in the respective age groups within the country populations served as an acceptable proxy for the distribution in the patient population.

Another objection may be that, for a patient to be considered eligible for a PA RCT, their cancer must be at a stage compatible with physical exertion and that more advanced BCs are associated with lower privilege [ 137 ]. Hence, RCTs with exercise often include patients with higher SES (education) because they have less advanced BC. However, this claim confirms the importance of putting focus on representativeness in RCTs targeting an already socially skewed patient population; it is important to be even more aware of sample representativeness to avoid excessive bias by favouring the already privileged. Likewise, employing already skewed patient populations as a reference could promote further social inequalities in health. Nonetheless, if the reference ratio for assessing representativeness was 1.22 [ 17 ], it would be possible to accept 22% more high-education patients before claiming misrepresentation of less privileged groups. However, according to our results, based on patients’ educational levels, approximately 45% of the included studies would still be considered biased in favour of the most privileged patients.

SES and PA Intervention Adherence

A proper body of articles with analyses of the association between SES-related characteristics and adherence was expected, and also that these articles would provide a basis for a synthesised examination of this relationship. However, the fact that only 6 studies investigated this association suggests that this question is perceived to be of little relevance in the field of BC and PA research. A previous review on the representativeness of RCTs reported no socioeconomic misrepresentation in oncology studies [ 4 ] however, our interpretation is supported by the fact that the review included only articles that provided a representativeness analysis, which the oncology articles had omitted in the case of SES.

No clear trend of associations between SES-related factors and adherence was seen across the six aforementioned studies, and the small number of studies and the differences between them hampered a clear conclusion. Previous studies have argued that poor representativeness may explain a lack of associations between SES and adherence rates [ 138 , 139 ]. In the current data set, there was no clear association between representativeness and SES-adherence associations. However, the small number of relevant articles formed an overly scarce base for reliable and conclusive analyses of this research question.

A tendency for studies that found a positive relationship between SES-related factors and adherence to report on longer interventions and to calculate adherence in terms of rates of attendance was observed. Three studies reported that the adherence rates decreased over time [ 97 , 104 , 107 ]. Previous results support the interpretation that time is a barrier to participation in PA interventions [ 53 , 140 ]. Strazdin et al. have substantiated how availability of time may have a larger impact on low-SES women in general [ 141 , 142 ]. Hence, the limited availability of time over a prolonged period may partly explain why less privileged patients have poorer adherence in such trials than their privileged counterparts.

Reasons for refusing to participate, or reasons for withdrawing, were not registered in our study. We should not ignore the fact that researchers experience real obstacles in recruiting of less privileged patients, so non-representative samples should not be seen as unwillingness or lack of effort to include the less privileged. There are reasons to believe that reasons for refusal to participate in the articles included coincide with the most common barriers previously reported [ 10 , 64 , 131 ] . However, although participation is voluntary and individual motivation or barriers are relevant, the adherence rates and the current social group distribution of patients in RCTs with PA may also be affected by the intervention design and the inclusion criteria defined by the researchers of each individual study [ 64 ].

All the included studies reported LTPA interventions. Considering that low-SES groups engage less in LTPA [ 47 ], it is reasonable to expect that low-SES patients were less inclined to participate in, and complete, such RCTs. Hence, a preponderance of RCTs employing exercise interventions could be perceived as being in favour of privileged patients. The searches of the current study did not, however, include search terms covering other PA domains and may thereby have strengthened the impression that LTPA is the prevailing protocol in RCTs of PA in BC patients. However, although many patients return to work during their first-year post diagnosis, RCTs designed for other PA-domains would not be verifiable as the patients’ level of PA would differ too much to control. In addition, the control group would have to be inactive within these PA-domains, which would be a requirement almost impossible to implement. The probability that many published RCTs of other types of PA exist, thus altering our results, is therefore small.

Consequences of Enhanced Selection Bias in Favour of Privileged Patients

Provided that our results reflect reality as they are based on synthesised data from a large set of systematically selected articles, social equity is a challenge to PA trials in BC patients. A stepwise, albeit unintended, social exclusion process causes attrition bias and a successive decrease in external validity, (i.e., the results are even less valid for individuals in other social groups than those who have completed the intervention when the intervention is finalised) [ 65 ]. Thus, PA-treatment is also less adaptable to patients in the same groups as those who withdraw. Drawing on the fundamental cause theory [ 143 ], these mechanisms show how affluent people could benefit more, in this case, from PA research, because studies serve the interests of these groups more than they care for all SES-groups. In addition, insignificant results from sub-analyses of social group-differences may be misinterpreted because the distribution of social groups in the samples does not mirror real life. This may disguise the possible fact that although all patients, by policy, should have equal access to health services, PA treatment interventions may not be suitable for all. An “inverse PA research law” analogous to the “inverse healthcare law” [ 144 ] describes how PA research interventions, initiated with the intention to treat a patient population, regardless of social status, nevertheless attend to privileged groups more than the less privileged who initially are prone to poorer health and thus more entitled to clinical research.

Strengths and Limitations

The major strength of this research is the thorough and systematic search of eligible studies, including traditional, and both BCB and FCB searches. To avoid our searches and not be included, an article would have to be published in a journal that is not indexed in any of the chosen databases, not be identified by the search terms, not be included in either the reference lists of the articles included from the descriptive searches or not have cited the articles included from the descriptive searches. It is possible that some articles were lost. However, it is less likely that any articles not included would be systematically more representative compared with the articles included.

The sample sizes in one-third of the studies were <50, seemingly decreasing the validity of our conclusions. However, rather than being a shortcoming of our study, the limitation is applicable to each RCT because the small samples, among other factors, hamper representativeness analyses such as ours. Hence, our analyses were based on the publication reality, whatever flawed original data materials.

SES and social privilege classifications vary across cultures, research fields, and public statistics, and they may cause imprecise standards for comparisons between studies of different origins. Nevertheless, our results present the big picture of misrepresentation across social groups with a precision sufficient to boost the debate within the scientific community.

Less educated, unmarried and non--white individuals may be underrepresented in BC PA RCTs, and SES-adherence associations in such trials are inconclusive. Unintentional social misrepresentation may create disguised inequity, warranting revived attention to this issue.

The current study provides a departure point for intensified attention to representativeness in RCTs. It should act as motivation both for seeking improved external validity, and for reconsidering whether LTPA in BC treatment is suitable for all.

Author Contributions

RS and MD made substantial contributions to the study: RS conceived the idea of the study, including its design, methodology and analysis. MD and RS performed descriptive- and FC searches, and BC searches, respectively, and the subsequent inclusion/exclusion of articles. RS and MD performed the analyses. RS drafted the manuscript. RS and MD reviewed and edited the manuscript and approved the final version. All authors contributed to the article and approved the submitted version.

The author(s) declare that no financial support was received for the research, authorship, and/or publication of this article.

Conflict of Interest

The authors declare that they do not have any conflicts of interest.

Supplementary Material

The Supplementary Material for this article can be found online at: https://www.ssph-journal.org/articles/10.3389/ijph.2024.1607002/full#supplementary-material

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Keywords: sampling bias, social validity, research equity, exercise trials, breast cancer, mammae cancer, meta-analysis

Citation: Stalsberg R and Darvik MD (2024) Social Representativeness and Intervention Adherence—A Systematic Review of Clinical Physical Activity Trials in Breast Cancer Patients. Int J Public Health 69:1607002. doi: 10.3389/ijph.2024.1607002

Received: 21 December 2023; Accepted: 10 April 2024; Published: 09 May 2024.

Reviewed by:

Copyright © 2024 Stalsberg and Darvik. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

*Correspondence: Ragna Stalsberg, [email protected]

Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.

Open access
Published: 16 May 2024

Characteristics of built food environments associated with alternative protein food choices: a systematic review

Hanna Zaleskiewicz 1 ,
Ewa Kulis 1 ,
Maria Siwa 1 ,
Zofia Szczuka 1 ,
Anna Banik 1 ,
Francesca Grossi 2 ,
Polymeros Chrysochou 3 , 4 ,
Bjørn Tore Nystrand 5 ,
Toula Perrea 4 ,
Antonella Samoggia 6 ,
Arlind Xhelili 2 ,
Athanasios Krystallis 4 &
Aleksandra Luszczynska ORCID: orcid.org/0000-0002-4704-9544 1

International Journal of Behavioral Nutrition and Physical Activity volume 21 , Article number: 58 ( 2024 ) Cite this article

Metrics details

This systematic review contributes to the understanding of the characteristics of built food environments that may be associated with choices of alternative protein foods (APF). Using the built food environment typology proposed by Downs et al., we investigated various environmental structures (e.g., supermarkets, other retailers, farmers’ markets, restaurants, schools, and online vendors) and the characteristics that may facilitate or hinder consumers’ choices. For example, facilitators and barriers may refer to the physical characteristics of environmental structures, food presentation practices, the organizational strategies or policies operating in the setting, or the actions that retailers or consumers engage in while selling, serving, choosing, trying, or purchasing APF in these environmental structures.

A systematic review (PROSPERO database preregistration; no. CRD42023388700) was conducted by searching 13 databases for peer-reviewed journals focusing on the fields of economics and business, agriculture, medical sciences, and social sciences. Data searches, coding, and quality evaluations were conducted by at least 2 researchers. A total of 31 papers (36 original studies) were included. The risk of bias was evaluated with the Joanna Briggs Institute quality evaluation tool, with 24 publications presenting low risk of bias.

The findings indicate that perceived and actual availability facilitate consumers’ APF choices across a built food environment. Several barriers/facilitators were associated with APF choices in specific types of built food environments: the way food is presented in produce sections (supermarkets), consumer habits in terms of green and specialty shopping (grocery stores), and mismatches among retailer actions in regard to making APF available in one type of food environment structure (e-commerce) and consumers’ preferences for APF being available in other food environment structures (supermarkets, grocery stores). The effect of a barrier/facilitator may depend on the APF type; for example, social norms regarding masculinity were a barrier affecting plant-based APF choices in restaurants, but these norms were not a barrier affecting the choice of insect-based APF in restaurants.

Conclusions

Addressing barriers/facilitators identified in this review will help in developing environment-matching interventions that aim to make alternative proteins mainstream.

Trial registration

PROSPERO database registration: #CRD42023388700.

As highlighted by the EAT-Lancet Commission Report [ 1 ], the role of food in shaping human health and environmental sustainability is pivotal. The dietary shift that is key to securing healthier societies and more sustainable food production can be achieved by reducing the consumption of animal-based proteins (such as meat) and incorporating alternative protein sources (e.g., plant-based) into the daily diet [ 1 ]. For example, the EAT-Lancet Commission Report [ 1 ] suggested that transitioning from a diet where meat constitutes the main protein source to a diet with plant-based proteins would substantially reduce any-cause mortality risks, as well as the risk of stroke, type 2 diabetes, and cardiovascular diseases. Considering greenhouse emissions, land use, energy use, and acidification potential, soybeans, legumes, grains, and vegetables rich in proteins have the lowest environmental effects per serving, whereas meat from ruminant livestock has the greatest environmental effect [ 1 ]. Alternative protein foods (APF) encompass a wide range of protein concentrates derived from various sources, such as insects, krill, microbial biomass, mushrooms, fungi, and plants such as peas or rapeseed [ 2 ]. The term “alternative protein” often excludes cultured meat due to the ongoing debate about the environmental benefits of its production [ 2 ].

The concept of the “food environment” is usually applied to investigate linkages among built environment, social, and political contexts and dietary choices and their consequences for human health and the natural environment [ 3 , 4 , 5 , 6 ]. The physical built environment has a prominent role in the overall food environment [ 5 , 6 ], and its characteristics constitute a setting where the social and political contexts operate together [ 7 ]. The various taxonomies explaining the physical food environment exhibit some similarities. For example, McKinnon et al. [ 6 ] categorized physical food environments into the following types: food stores, restaurants, schools, and worksite environments. A taxonomy proposed by Downs et al. [ 5 ] considers formal structures, such as supermarkets, hypermarkets, other retailers, farmers’ markets, restaurants, institutional and public procurement settings, mobile vendors, and online vendors, as well as informal environmental structures such as wet markets.

Between 2013 and 2022, major retailers (e.g., Walmart, Carrefour, and Tesco) started selling their own plant-based alternative protein food ranges, whereas major fast food companies (e.g., Yum!, the owner of KFC and Pizza Hut) have established commercial relationships with plant-based food producers and launched plant-based protein products [ 3 ]. In 2022, Burger King opened its first plant-only outlet in London, England [ 3 ]. Thus, APF is becoming more readily available for consumers in various built food environmental structures.

In addition to identifying where specific dietary choices occur (e.g., [ 5 ]), taxonomies of the built food environment should be complemented by the evidence-based characteristics of the respective structures that may facilitate or hinder dietary shifts toward specific choices (e.g., an increase in APF intake). The latter approach is in line with the context and implementation of the complex intervention approach [ 7 ], which highlights the role of the setting (a structure in a physical environment) and its contextual characteristics in codetermining the efficacy of any actions promoting new nutrition behaviors. The built food environment taxonomy proposed by Downs et al. [ 5 ] assumes that the characteristics of the food environment may include general features of built environment structures (e.g., availability, affordability, and sustainability of food products). Other approaches indicate that the characteristics of the “setting” (or the structure of the built food environment) may be divided into macro- (e.g., national policies addressing respective settings), meso- (e.g., ale strategies adopted by a retail chain), and microlevels (individual) [ 7 ]. Characteristics at the individual level may refer to the attributes of various food system actors (e.g., producers, retailers, and consumers).

Existing systematic reviews have explored the associations between behaviors such as increased intake of plant-based proteins or meat reduction and food promotion strategies (e.g., the recipe design, product labeling, or sensory characteristics of APF). For example, a review of 18 intervention studies investigated the microenvironmental characteristics associated with reducing meat consumption [ 8 ]. Strategies such as reducing meat portion sizes, altering the sensory characteristics of meat and meat alternatives, and providing meat-free options were associated with a reduction in meat intake. Notably, making meat alternatives available has been found to have a sustained effect [ 8 ]. Similarly, Stiles et al. [ 9 ] reviewed the effectiveness of strategies aimed at decreasing animal protein food and increasing plant protein food in food service settings, including menu redesign (increasing availability of nonmeat proteins on the menu), recipe redesign, service redesign (to improve sustainability), menu labeling (e.g., “a climate choice”), and prompts at the point of sale (e.g., “dish of the day”). The menu offer redesign strategy demonstrated the most substantial and significant effects [ 9 ].

Findings from previous reviews [ 8 , 9 ] indicated that increased availability of APF facilitated changes in protein intake (meat reduction and increased plant protein intake). However, these reviews do not provide insights into whether these effects apply across different built environments (e.g., school canteens, restaurants, or supermarkets) or whether certain strategies are more impactful in specific settings (e.g., restaurants vs. supermarkets). Furthermore, these reviews do not delve into the barriers that may hinder APF uptake, and it remains unclear whether these findings can be generalized to other APF products, such as insect-based APF.

The intake and acceptability of insect-based APF in developed countries differ from what has been observed for African, Latin American, and Southeast Asian countries [ 10 ]. Consumers in the latter countries collect insects from uncultivated wild areas and sell them via informal markets [ 5 ]. These practices contrast with the strictly regulated formal market of insect-based APF in Western countries [ 11 ]. Due to these differences in the physical food environments where APF choices occur, our review focuses on built food environments in Western countries and developed Asian countries with strictly regulated formal APF markets (i.e., Japan).

The literature lacks a synthesis of evidence of characteristics that may be linked to an increase in the uptake of APF in specific settings. It remains unclear whether these characteristics are common or specific for some physical environmental structures and whether they are generalizable across different types of alternative proteins (e.g., plant-based vs. insect-based APF). A synthesis of evidence aids in the development of interventions promoting APF by identifying evidence-based characteristics that may facilitate or hinder APF consumption.

Using the systematic review method, the aim of this study was to identify the characteristics of the structures of the built food environment that may act as either barriers or facilitators for choosing APF products. In particular, we investigated (a) informal market food environments (wet markets, street vendors, kiosks, and mobile vendors) and (b) formal market food environments (supermarkets, hypermarkets, retailers, farmers’ markets, restaurants, institutional public procurement settings, mobile vendors, and online vendors) (cf. [ 5 ]). Furthermore, we sought to explore any built food environment characteristics that have been tested for their associations with consumers’ APF choices.

Materials and general procedures

This study was conducted following the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) [ 12 ]. The findings presented are part of a broader systematic review, which was registered with the PROSPERO database under the registration number #CRD42023388700. The overarching goal of this systematic review is to identify the physical environmental characteristics related to consumers’ APF choices.

Search strategy

We conducted a systematic search of 11 databases containing peer-reviewed journals from the fields of economics and business, agriculture, medical sciences, and social sciences (Academic Search Ultimate, PsycInfo, PsycArticles Business Source Ultimate, Agricola, GreenFILE, Health Source: Nursing Academic Edition, SocINDEX, MEDLINE, MasterFILE Premier, and Academic Research Source eJournals), which were accessed through the EBSCO platform. Separate searches of 2 additional databases, Web of Science and SCOPUS, were conducted following the primary search. Our search included documents and articles published up to March 2023.

The search strategy adopted three groups of keywords: (1) alternative protein food (e.g., "seaweed*" OR "alga*" OR "insect*" OR "lupin*" OR lentil* OR "mealworm”), (2) physical built environment (e.g., "shop*" OR "retail*" OR "cater*" OR "restaurant*" OR "supermarket") and (3) consumer or behavior-related (e.g., "intake" OR "food" OR "consume*" OR "eat" OR "sale") keywords. For the full list of keywords, see Additional File 1. These keywords were selected using existing reviews on APF [ 13 , 14 , 15 ] and the food environment typology by Downs et al. [ 5 ]. Researchers from the fields of consumer sciences, food sciences, and nutrition from the LIKE-A-PRO consortium were consulted regarding the appropriateness of the keywords [ 16 ].

The feasibility of the search string was pretested across the databases before the search was initiated. The aim of this approach was to capture a wide range of relevant articles across the databases. This approach increased the number of identified entries and, thus, minimized the likelihood of excluding relevant documents during the initial screening stages.

To ensure the robustness of the search, we performed manual searches of references within the full texts of original studies assessed for inclusion, as well as complementary nonsystematic searches of Google Scholar using the same keywords as used in the databases. Finally, we searched the CORDIS and Open Research Europe (ORE) databases for open peer-reviewed articles. The keywords were modified to fit the character limits (up to 50 characters in length) imposed by CORDIS and ORE.

Inclusion and exclusion criteria

The following inclusion criteria were applied: (1) peer-reviewed English-language original quantitative or qualitative studies; (2) studies addressing alternative protein-based foods, including proteins that are land or sea plant-based, fungi-based, bacteria-based, or based on any other alternative protein sources, such as krill, as well as combinations of meat- and plant-based proteins; and (3) studies investigating built and/or physical environmental structures, based on the built food environment typology by Downs et al. [ 5 ], where European consumers made choices regarding APF. Original studies were included if (4) they discussed any type of link between the characteristics of the food environment and any (a) indicators of consumers’ choices, such as perceived display/ways of exhibiting food in the built environment, intention to buy, intention to eat, actual intake, and actual sales, or (b) indicators of food availability in the respective food environment.

The exclusion criteria were as follows: (1) studies that did not report any original data, such as reviews or position papers; (2) dissertations, protocols, conference materials, or book chapters; (3) studies focusing solely on reducing meat intake without investigating how proteins will be supplemented in the diet by APF products; (4) studies focusing on increasing the intake of fruits or vegetables without specific data on plant-based protein sources; (5) studies solely addressing the physical environment in Asia, Africa, or South America, entailing locally collected wild-living insects and their local consumption or local retail; (6) studies involving novel foods without mentioning that the food is made of/with alternative protein sources, e.g., novel drinks based on sea buckthorn; (7) studies addressing consumers’ choices regarding laboratory-based, in vitro-grown meat, with no alternative proteins added; (8) studies focusing on geographical factors, such as between-country or between-region differences; and (9) studies investigating APF as supplements or animal feed.

Data collection and extraction

Figure 1 illustrates the data selection process. The databases were independently searched by three researchers (HZ, EK, MS), and the searches were unsystematically checked by a fourth researcher (AL). The initial search yielded k = 7,935 records obtained from searches of 11 databases using the EBSCO search engine, k = 838 from the Web of Science, and k = 6,680 from SCOPUS. All abstracts were screened by two researchers (randomly assigned from a group of five researchers, HZ, EK, ZS, MS, and AB) to identify potentially relevant studies. Any conflicts regarding the inclusion of a document were resolved through discussions with a fourth researcher (AL). Next, three researchers (AL and two randomly assigned researchers from a group of five researchers—HZ, EK, ZS, MS, and AB—independently read the full-text versions of the articles and determined their match with the inclusion criteria. Additional searches for original peer-reviewed studies were conducted through screening the references of articles evaluated for inclusion independently by PC and TP and searching Google Scholar, CORDIS, and ORE databases (conducted by AL or HZ).

PRISMA flow diagram of the article search and selection process for the systematic review

Thirty-one publications reporting 36 independent studies were included (Fig. 1 ). Two articles [ 17 , 18 *] reported findings from the same study; only the latest publication [ 18 *] was included. We included two original studies reported in a publication by Vandenbroele et al. [ 19 *], three original studies reported by Motoki et al. [ 20 *], and three original studies reported by Baker et al. [ 21 *].

The following data were extracted to address the study’s objectives: study population characteristics, country of data collection, design of the original study and type of methods used to collect data, the period when the data were collected, the type of alternative proteins investigated, the type of built environment and its characteristics, indicators of the consumers’ choices, and key results (see Supplementary Table 1, Additional File 1). Data extraction was conducted by two researchers (HZ and AL). Any disagreements during these stages were resolved by a consensus method (searching for possible rating errors, followed by discussion and arbitration by a third researcher, AB) [ 22 ].

Data coding, analysis, and synthesis

The data retrieved from each original study were coded according to four categories: (1) a type of alternative protein food products; (2) a type of built food environmental structure; (3) a characteristic of the built food environment that was related to consumers’ choices of alternative proteins; and (4) a type of the consumers' choice indicator. Additional File 1 presents the definitions, theoretical background, and categories applied during the coding procedures.

The included material was heterogeneous for each type of built environmental structure (e.g., supermarkets) in terms of consumers’ choice indicators, types of alternative proteins, and built environment characteristics. Therefore, a meta-analysis was not feasible. We employed narrative synthesis methods instead [ 23 , 24 ] (for details, see Additional File 1).

Risk of bias and quality assessment

The methodological quality and risk of bias in the included studies were assessed using the Joanna Briggs Institute Critical Appraisal Tools [ 25 ] for both cross-sectional and qualitative studies. These tools are appropriate for evaluating qualitative and quantitative cross-sectional studies (no observational longitudinal studies were included, k = 6 manuscripts reported experimental studies). Each study was evaluated based on eight criteria and overall quality (good, fair, or poor). For details, see Additional File 1.

The methodological quality (risk of bias) of the included publications and respective studies was assessed by two pairs of independent reviewers (PC and TP or AB and MS). Studies were scored according to the critical appraisal questions. Disagreements were resolved by discussion or by consulting a third researcher (AL). The overall risk of bias for the included studies was determined using the following cutoffs: low risk of bias, if at least 70% of the assessed criteria were met; moderate risk, if 50–69% of the criteria were met; and high risk, if less than 50% of the criteria were met.

Description of included studies

A total of k = 36 original studies were included. Additional File 1 presents the general descriptive information about the included studies and the results of coding referring to consumer choice indicators (e.g., acceptability, intention to eat, intention to buy, etc.). The enrolled populations were heterogeneous, with a total of N = 113,984, sample sizes ranging between 15 and < 100,000 (M = 3,453.09; SD = 17,344.40), and ages ranging from 7 to 90 years. Almost half of the studies were cross-sectional ( k = 15, 41.6%), k = 11 (30.5%) were experimental, k = 9 (25%) were qualitative, and k = 2 (5.5%) were mixed method studies.

Types of APF addressed in the original studies

Across the original studies, k = 17 studies discussed plant-based alternative protein products, k = 15 studies addressed insect-based alternative protein products, k = 1 accounted for hybrid meat products (with meat and plant-based meat replacement combined), k = 4 analyzed foods from a combination of either plant-based proteins or insect-based sources, and k = 3 focused on a broader category of novel food, including either plant-based or insect-based APF or APF from various sources.

Built environmental structures studied in the included research

None of the studies addressed informal market structures (wet markets, street vendors, kiosks, or mobile vendors), whereas k = 31 (all studies) addressed the formal market food environment. In particular, k = 6 studies addressed supermarkets, k = 10 discussed other food retailer structures (e.g., grocery stores), k = 2 addressed farmers’ markets, k = 17 addressed restaurants, k = 2 addressed institutional and public procurement (schools) settings, k = 4 addressed online vendors, k = 1 addressed vending machines, and k = 4 addressed food festivals.

The risk of bias

The findings indicated that 24 of the included publications presented a low risk of bias, three studies had a moderate risk, and four studies had a high risk of bias (for details, see Additional File 2). An interrater reliability analysis between the independent reviewers’ scores was performed using Cohen’s kappa (values larger than 0.60 indicate strong agreement). The analysis showed strong agreement between the two raters, with κ = 0.69 (95 CI: [0.42, 0.96]). No study was excluded on the basis of the quality assessment.

Findings for the formal market food environment

The extracted data were organized using the following grouping categories: (a) type of physical built environmental structure, using Downs et al.’s [ 5 ] taxonomy, and (b) type of organizational characteristics of the setting, i.e., meso-level (e.g., availability, product location, and promotion strategies used in the setting), as well as microlevel (e.g., stakeholders’ perceptions of availability, social norms, shopping habits, preferences for location, and occasion to eat APF) [ 7 ]. The findings for different types of APF (plant-based, insect-based, and other APF sources) are discussed separately to determine potential differences.

Supermarkets

The characteristics of supermarkets linked with consumers’ APF choices were reported in six studies [ 26 ,* 27 ,* 28 ,* 29 ,* 30 ,* 31 *]. Three studies discussed plant-based alternative proteins, and three discussed insect-based proteins. All studies focused on the APF presentation in supermarkets, the period during which a product was available for sale, and the availability of the products.

Availability (plant-based APF)

The number of APF products available in supermarkets has been on the rise. For example, Australian data indicate a doubling of APF (130% increase) between 2014 and 2021, with a 150% increase in plant-based meat replacements. However, the availability of tofu products has decreased over time [ 26 *]. Most APF products have been available in supermarkets for an average of two years [ 26 ,* 27 *]. Sausage is the most popular plant-based meat replacement [ 27 *].

Product location, APF promotion, and ease of finding APF (plant-based APF)

Plant-based meat alternatives are allocated a less shelf space than other protein products. Plant-based APF products are placed in less prominent sections of supermarkets and are perceived as “hidden” by consumers. They are also less likely to have sale, quality, or promotional signage compared to traditional meat products [ 28 *]. Plant-based meat alternatives are often placed in produce (fruits/vegetables) sections or among high-end products [ 28 *].

Plant-based meat alternatives are perceived as difficult to locate in stores, especially compared to meat products, which is also attributed to inconsistencies in their placement within and across retail chains [ 28 *].

Retailers’ beliefs and practices (plant-based APF)

Supermarket retailers await clear demand signals before introducing new APF products [ 28 *]. Retailers believe that including APF in dairy and meat sections will reduce supermarket profits, and placing APF-based meat substitutes away from meat sections may address the concerns of vegetarians and vegans [ 28 *].

Shopping habits and preferred location for intake (plant-based APF)

Consumers who typically purchase protein products in upscale supermarket chains are willing to pay more for plant-based APF products [ 29 *]. In contrast, those who usually shop in discount supermarkets were less willing to pay for APF products, possibly due to lower quality perceptions [ 29 *].

Retailers focus on e-commerce and perceived availability in supermarkets (insect-based APF)

For consumers, the focus of retailers on selling via e-commerce instead of in supermarkets may be perceived as a barrier [ 30 *]. To enhance consumer trust and confidence, the widespread distribution of insect-based APF products in supermarkets and other grocery stores is recommended [ 30 *]. Finally, consumers report that the lack of availability of insect-based APF in supermarkets is a barrier to the intention to eat [ 31 *].

Grocery stores/other types of shops selling food

The characteristics of grocery stores associated with consumers’ choices of alternative protein food were reported in 11 studies, reported in nine publications [ 18 ,* 19 ,* 21 ,* 27 ,* 32 ,* 33 ,* 34 ,* 35 ,* 36 *]. Six studies discussed plant-based alternative proteins, while five discussed insect-based proteins. The research focused on the APF presentation at retail points, the perceived availability of products, the preference for the type of point of sale/retail, and consumer shopping practices, including “green” shopping, specialty food shopping, and shopping off campus (students).

Product location and promotion (plant-based APF)

The placement of APF on shelves with vegetarian food or in produce departments results in lower sales of APF, while higher sales occur when the APF is placed in the meat section [ 19 *]. In addition, an increase in APF sales was also achieved when sandwiches made with plant-based APF were placed in the same refrigerator as sandwiches with meat (compared to a separate refrigerator) or in a refrigerator visible from the shop entrance (versus with its back to the entrance) [ 19 *].

Perceived availability (plant-based APF)

The perceived availability of food in locations where food is usually purchased is related to satisfaction with plant-based proteins [ 32 *]. Research revealed that 25% of respondents indicated “not available where I usually buy food” as a key barrier to trying new plant-based APF [ 33 *]. Furthermore, consumers who intended to purchase such foods claimed that the availability in their usual food shopping places was low. Availability was a significant factor for those respondents who were likely to purchase new protein alternatives, but it was weakly associated with consumer choice indicators among undecided consumers [ 33 *].

Shopping habits (plant-based APF)

The level of approval of plant-based APF was greater among customers who regularly shop in specialty food stores [ 18 *]. Students who shopped for food in grocery stores located outside of university campuses were more likely to purchase plant-based APF than those who shopped on campuses [ 35 *].

Product promotion (insect-based APF)

Research has indicated no major differences in the intention to purchase or expected fondness for/attractiveness among products with visible insects on the package vs. pictures of an insect-based powder and a Latin name [ 21 *]. Notably, the levels of intention to buy insect-based APF were relatively low [ 21 ,* 34 ,* 36 *].

Preferred location for availability and shopping habits (insect-based APF)

Consumers indicated their preference for the availability of insect-based APF across different food outlets, such as grocery stores, convenience stores, and petrol stations, and disagreed that such products should be available via e-commerce only or in specialty shops [ 27 ,* 36 *]. Frequent “green shopping” in grocery stores was positively associated with a greater willingness to buy, fondness for, and willingness to pay for APF [ 34 *].

Farmers’ markets

Only two studies have investigated the characteristics of farmers’ markets linked to consumers’ APF choices [ 26 ,* 27 *].

Preferred location for APF purchases

Porretta et al. [ 27 *] reported that older consumers were willing to buy insect-based APF if they were available from local producers selling their products in small markets. In contrast, Aerni et al. [ 26 *] reported that points of sale at railway stations in large cities (e.g., Zurich) had greater sales of plant-based alternative food than did small farmers’ markets in the same cities.

Restaurants

Seventeen studies (reported in 14 publications) addressed restaurant characteristics in relation to consumers’ choice of APF [ 18 ,* 20 ,* 21 ,* 37 ,* 38 ,* 39 ,* 40 ,* 41 ,* 42 ,* 43 ,* 44 ,* 45 ,* 46 ,* 47 *]. Six focused on plant-based APF, five focused on insect-based APF, and six discussed APF from various sources. The investigation addressed preferences for restaurants, such as APF environments, a prognosis of availability by experts, consumer social norm conformity, restaurant image creation and promotion, and meal presentation.

Experts’ perceptions of the popularity of plant-based and insect-based APF

Research investigating haute cuisine restaurant trends suggested that expert panels (selected on the basis of their entry on the official Michelin Guide website) predict that alternative proteins (insect- and plant-based) will become a strong trend in major European restaurants [ 47 *]. These experts anticipate that plant- and insect-based proteins will be served to a greater extent than in vitro/cultivated meat. Additionally, the trend toward using locally sourced ingredients is expected to continue, with ingredients from distant regions playing a less important role [ 47 *].

Experts’ actions to create a positive social image of plant-based APF

Creating a positive social image for restaurants is a strategy for increasing consumer interest. For example, renowned chefs have recognized the potential of using microalgae-based APF as an ingredient in their cuisines since there is a growing audience of consumers interested in food novelty who identify themselves with chefs’ discourses about sustainability, ethnicity, and authenticity [ 46 *]. Such celebrated restaurants may also help popularize the use of plant-based APF in casual or mid-range restaurants, as well as home-based dining [ 46 *].

Perceived availability of plant-based APF

Perceived availability in the restaurant was identified as a determinant of consumers’ decisions to purchase plant-based APF in these restaurants. For example, consumers’ perceptions that plant-based APF is easy to find on restaurant menus were associated with a greater willingness to pay for this type of food [ 45 *].

Eating-out habits and preferred location, occasion, and company for consumption (plant-based APF)

A greater frequency of eating in restaurants was related to a greater willingness to pay for plant-based meat alternatives [ 37 *]. Among women, a higher frequency of dining out/going to restaurants with friends and family was related to perceiving microalgae-based food as healthy, sustainable, and nutritious, whereas among men, it was related to unfavorable perceptions (e.g., limited healthiness or nutritional values of algae-based foods) [ 18 *]. The findings regarding gender differences align with previous research indicating that higher masculinity is associated with lower acceptance of social eating situations (e.g., restaurants) involving the consumption of nonmeat products among men [ 40 *]. Weinrich and Elshiewy [ 18 *] also noted that the relationship between APF perceptions and the frequency of dining out/going to restaurants with friends and family may also depend on the country where the study was conducted.

Research highlights the relevance of social norms and the social context in the consumption of plant-based APF in vegetarian/vegan restaurants [ 40 *]. Young meat-eating men were more likely to eat plant-based APF burgers in vegetarian restaurants when encountering specific social cues, such as the presence of other men queuing for a veggie burger or dining with a female romantic partner [ 40 *]. Conversely, visiting such restaurants and portraying oneself as dining in a vegetarian restaurant on social media was seen as a threat to masculinity [ 40 *]. In line with this, omnivores and flexitarians indicated low acceptance rates for eating plant-based APF while dining in restaurants or during business lunches with coworkers [ 44 *].

Consumers report that eating plant-based APF in more casual, private situations may be perceived as more appropriate than consuming this type of food during more celebratory occasions [ 44 *]. These eating occasions may take place at home or in pubs, bars, or restaurants. For omnivores and flexitarians, eating alone, with friends, or with family members on a weekday is perceived as the best (and equally appropriate) environment to eat plant-based meat alternatives [ 44 *]. However, for omnivores and flexitarians, eating plant-based meat alternatives for a family Sunday meal or at a barbecue party received similar, low appropriateness ratings [ 44 *]. These results echo similar findings obtained by [ 40 *], who highlighted the influence of social norms on the purchase of plant-based meat alternatives in restaurants.

Eating-out habits and preferred location, occasion, and company for consumption (various types of APF)

Restaurants were indicated as the second most preferred place for consumers to try various types of novel food, including insect-based and plant-based APF (food festivals were the most preferred, and homes, cafés, pubs, and bars were less preferred locations) [ 20 *].

Availability of locations serving insect-based APF

Insect-serving restaurants were perceived as relatively rare, with only 31% of consumers agreeing that some European gourmet restaurants incorporate edible insects into their food preparation [ 42 *].

Experts creating a positive social image of restaurants (insect-based APF)

The use of APF can serve as a strategic promotional tool for restaurants. This strategy may include pushing boundaries with unusual ingredients, encouraging customers to try small portions of novel foods, and offering refunds if the meal is unsatisfactory [ 41 *]. Applying such strategies conveys a greater sense of freedom of choice to customers [ 41 *]. A positive image of edible insect restaurants was related to a stronger intention to eat insects [ 43 *]. Furthermore, being an environmental advocate (the ability to convince others to act for environmental conservation) was related to a better image of insect-serving restaurants [ 43 *].

Studies have shown that the presence of visible insects in restaurant-served meals leads to a lower intention to purchase, lower expected liking, and lower attractiveness of the food compared to food with invisible insects and vague descriptions of insect-based ingredients [ 21 *]. Restaurants serving insects often employ strategies such as name ambiguity for meals containing insects and deliberate beautification during their presentation (e.g., garnishing to obscure ingredients and reduce neophobic tendencies) [ 41 *]. The absence of visible insects in restaurant-served meals was related to low perceived risks [ 21 *] and low anxiety while eating the respective types of foods, which resulted in stronger intentions to (re)visit restaurants serving insect-based APF [ 38 *].

Preferred location and company for consumption (insect-based APF)

Restaurants are perceived as the preferred places to eat insect-based APF products. When asked about how they would eat food made with edible insects, the majority of consumers stated, “with an expert”, followed by “in a restaurant”, and “with someone who knows how to prepare it” [ 39 *].

Two studies [ 48 ,* 49 *] focused on the availability of plant-based APF and the impact of school workshops among children aged 7–14 years. Other institutions or public procurement environments were not investigated.

Availability of plant-based APF

The studies revealed that public schools did not offer APF for lunch, whereas private schools offered them less than once per week [ 48 *].

Delivery of education interventions regarding insect-based APF

An approximately 20% increase in readiness to choose insect-based APF for lunch was observed among children after brief (45 min) workshops addressing the reasons for and context of eating insects, followed by insect-based APF tasting, being delivered at schools [ 49 *].

Online vendors

Four studies discussed aspects associated with consumers’ choices of APF [ 27 ,* 36 ,* 50 ,* 51 *], with all of them reporting on insect-based APF products.

Availability of insect-based APF

Insect-based APF sales predominantly occur through online retail channels, with European producers using e-commerce as a distribution channel five times more frequently than physical sale points [ 51 *]. However, this strategy may have consumer trust and credibility limitations. To enhance consumer trust and credibility, these products may need to be sold in supermarkets and local groceries instead of focusing on e-commerce [ 50 *].

Preferred location for the purchase of insect-based APF

When consumers were asked about their preference for the availability of insect-based APF across different food sale points, they generally disagreed with the idea that this type of food should be exclusively available through e-commerce [ 27 ,* 36 *].

Food festivals

Two studies [ 20 ,* 45 *] highlighted the significance of food events and food festivals as highly approved environments for plant- and insect-based APF.

Preferred location or occasion for purchasing/trying plant-based and insect-based APF

Regarding willingness to try plant-based meat alternatives, consumers indicated the highest willingness to try them at food festivals, followed by restaurants (lower at home, cafés, bars, and pubs) [ 20 *]. Consumers who reported an opportunity to consume seaweed or algae-based food during a gastronomic event or a trip are more likely to consume plant (algae)-based APF than those who did not participate in such events [ 45 *]. Potential consumers who were asked about their preferred location to try insect-based APF reported that they were most willing to try them during food festivals, whereas significantly lower levels were reported for trying them at home or in restaurants/cafés/bars/pubs [ 20 *].

Food vending machines

Research focusing on a specific type of food (algae-based breadsticks) suggests that customers consider this type of food a snack rather than a meal substitute and should be sold from vending machines [ 52 *].

Informal market environment: wet markets, mobile vendors, street vendors, kiosks, vending machines, and farmers’ markets

There is no evidence directly linking wet markets, street vendors, kiosks, mobile vendors, and consumers’ behaviors and intentions to buy/pay for plant-based or insect-based APF . It seems plausible that the European food market is mostly formalized due to national and European Union-level regulations referring to food safety, labeling, and quality, particularly those referring to novel foods (cf. the European Commission Implementing Regulation, 2018/456 of 19 March 2018 [ 53 ]).

Summary of findings

Table 1 summarizes the findings, focusing on (a) the structures of the built food environment where consumers make APF choices and (b) barriers to and facilitators for choosing plant-based and insect-based APF, operating in the respective structures. Barriers and facilitators refer to: the physical characteristics of environmental structures; food presentation practices; organizational strategies or policies operating in the setting; and the actions and beliefs of retailers or consumers while selling, serving, choosing, trying, or purchasing APF in these environmental structures. The synthesis of the evidence indicated potential differences between the characteristics of the structures of the built environment that may be relevant for plant-based APF (Fig. 2 ) and those that may be relevant for insect-based APF (Fig. 3 ).

Built environment barriers to/facilitators of plant-based alternative protein foods (APF) consumer choices

Build environment barriers to/facilitators of insect-based alternative protein foods (APF) consumer choices

Complementing the proposal of Downs et al. [ 5 ] that lists built environment structures relevant for all food choices, the findings of this systematic review provide an overarching synthesis of the characteristics that can either promote or hinder consumers’ choices of APF products in restaurants, supermarkets, grocery stores, schools, farmers’ markets, or at food festivals (see Table 1 ). Consistent with existing typologies [ 5 , 6 , 54 ] and systematic reviews [ 8 , 9 ], our study highlights that availability is the core characteristic of the built environment that facilitates consumers’ APF choices. Our review provides insights into how availability is shaped and how it influences the choices of different types of APF across different settings within the built food environment. Limited availability appears to constitute a common barrier observed across supermarkets, grocery stores, restaurants, and schools.

Our review indicates a mismatch between the APF supply and the APF demand that may be responsible for stagnated APF sales and low consumption. Retailers believe that increasing APF in supermarkets will harm profits [ 30 *], and their subsequent decisions to sell APF via e-commerce [ 51 *] result in low APF availability in groceries/supermarkets. Consumers, in turn, report low trust in products that are not available in grocery stores or supermarkets but are only available via e-commerce [ 50 ,* 55 ]. Consumers’ trust is a key determinant of buying and eating novel foods [ 56 ]. The limited availability of APF in locations where consumers usually shop for food results in low APF acceptance and low intention to buy or try APF [ 30 ,* 33 ,* 45 *]. Consumers are less likely to choose an APF if the APF is perceived as difficult to find in supermarkets/grocery stores/on restaurant menus [ 30 ,* 33 ,* 45 *]. The lack of actual availability of plant-based APF at schools [ 48 *] may also result from the low trust of consumers in novel foods such as APF.

The current systematic review highlights that barriers and facilitators are specific for both the type of built environment and the type of APF (plant-based vs. insect-based). Regarding the type of structure in the built environment, our review indicates several specific social facilitators and barriers that operate in restaurants. In terms of facilitators, restaurants are preferred locations to try novel foods for the first time [ 39 *], possibly because consumers perceive restaurants as places where experts prepare and serve food they can feel safe consuming [ 56 ]. The narrative created by chefs and the social image of restaurants promoting novel and sustainable foods [ 46 *] may facilitate the use of APF in restaurants. Moreover, consumers’ beliefs about the importance of the sustainability of APF are among the key individual-level predictors of consumers’ choices of APF (cf., e.g., [ 57 ]). In contrast, social norms of masculine behavior among young meat-eating men may act as barriers, particularly in official or business settings or when dining with meat-eating male friends [ 40 *].

Food festivals or gastronomic events emerge as specific types of food environmental structures where consumers may be willing to try APF [ 20 ,* 45 *]. Visiting food events or festivals may satisfy consumer needs of being adventurous, their curiosity or sensation seeking, which, in turn, are related to stronger intentions to try, greater attractiveness, and willingness to try APF [ 57 , 58 ]. While restaurants and food festivals/gastronomic events may be the locations where consumers first try an APF, the adoption of regular intake of the APF could depend on other structures, such as supermarkets and grocery stores—places where consumers typically buy their food—and the associated barriers and facilitators within these structures [ 33 *].

The findings highlight that certain barriers and facilitators may be relevant in specific types of built food environments where consumers try new foods but do not apply in environments where daily food shopping takes place. For instance, the lack of visible insects and the use of ambiguous names of insect-based APF in restaurants facilitated consumers’ choices, likely by reducing anxiety and increasing the likelihood of trying this type of APF in restaurants [ 41 *]. In contrast, the perceived attractiveness of insect-based APF was low regardless of insect visibility and package labeling of food sold in retail stores.

Our review also provides evidence for differences in facilitators of consumers’ choices to consume plant-based APF and insect-based APF. These differences are particularly evident when considering restaurants as built food environments. Social norms related to masculinity act as barriers to young men visiting vegetarian restaurants or buying and eating plant-based APF in restaurants or at business lunches [ 40 ,* 44 *]. Previous systematic reviews focusing on individual determinants of insect-based APF have indicated that young men and high sensation seekers are more likely to try eating insects [ 57 , 59 ]. Therefore, it is possible that social norms regarding masculinity could actually facilitate the consumption of insect-based APF in restaurants among young men.

The results provide no insights into the underlying mechanisms that explain the associations between barriers/facilitators and consumers’ APF choices in specific environmental structures. Unfortunately, such mechanisms were rarely investigated in the original studies. Thus, any discussion of the underlying processes remains hypothetical. It may be assumed that the potential mechanisms may include consumers’ motivations, emotions, and beliefs related to the APF; social and cultural norms about eating novel food; and habits related to buying and preparing any type of food. These mechanisms may be significant (or may be less relevant), depending on the type of physical environmental setting where the choice of APF occurs. For example, the effects of social norms may be stronger in a setting where consuming food is a social activity (e.g., in restaurants) than in a setting where an APF is purchased via a website of an online vendor. Consumers’ curiosity and sensation seeking may be significant drivers for trying new APF in novel environments such as food festivals. In contrast, curiosity may be less important when a consumer’s behavior is aimed at restocking breakfast supplies in a local grocery store. When shopping “on autopilot” (e.g., during routine weekend shopping at a local supermarket), automatic, nonreflective responses to cues may be the key mechanisms determining consumers’ choices. In this context, cues such as the retailer’s strategy of placing a product in a specific section may be among the strongest drivers of consumers’ choices. Future research should explore the common and specific mechanisms determining consumers’ choices across the structures of the built environment.

This study has potential implications for promoting APF choices. Our review lists characteristics of the built food environment to be considered in interventions targeting the initiation and adoption of APF intake. APF promotion strategies may be adjusted to specific types of barriers/facilitators operating in specific structures of the built environment. Furthermore, the results referring to the availability of APF may suggest changes in strategic considerations at the retailer level (for example, a shift from an emphasis on sales via e-commerce to supermarket sales). The results may also inform public health policies and address the physical food environment, helping to prioritize specific changes in the respective setting (e.g., positioning APF in meat and produce sections in supermarkets).

Our study inevitably has certain limitations related to the number, quality, and heterogeneity of the studies included. First, the number of studies we identified was limited, and replications across contexts (e.g., in different countries) are missing. Furthermore, most of the empirical evidence is based on correlation studies; therefore, causal conclusions cannot be drawn. The included research used a broad range of indicators of consumer choices, ranging from intention (to buy or to try/eat) to actual intake. Intention may have a limited effect on the adoption of a new consumer behavior and its maintenance over time [ 60 ] because intention is only moderately associated with respective food intake [ 61 ]. The quality of 22.3% of the included studies was moderate or low, which limits the reliability of the conclusions. To address publication bias, we conducted additional searches for grey literature (published in outlets other than impacted journals) via searches of the Google Scholar, CORDIS, and ORE databases. Approaches that allow us to quantify the heterogeneity of the results could not be used, as the data were analyzed using a narrative synthesis instead of a meta-analysis.

Future original studies may also need to control for potential confounders (e.g., economic factors such as disposable income in families and food policies operating in the respective countries) and address some methodological shortcomings. For example, specific barriers and facilitators were usually studied in one setting and one location only; hence, the generalizability of the results to other settings (e.g., other supermarket chains) and different locations (e.g., urban versus rural areas) is limited. The characteristics of consumers, such as lower income, may constitute a universal barrier to APF choices [ 62 ]. Higher prices of many APF (compared to animal-based protein products) may affect APF affordability among people with lower incomes, regardless of the setting where the purchase takes place. The original research was heterogeneous in terms of the socioeconomic status of the participants, and the effect of socioeconomic variables was usually not considered. Future research should account for the confounding role of economic factors.

Furthermore, the applied methods of the systematic review also have limitations. The use of narrative synthesis and to the inability to conduct a meta-analysis hindered the evaluation of the actual significance and strength of the relations between the characteristics operating in the respective types of built food environments and the indicators of consumers’ choices. Due to very limited empirical evidence for APF other than plant-based and insect-based APF, the proposed extension of the typology for the built environment does not provide insights into the characteristics of the food environment that may promote or hinder mainstreaming krill-based, fungus-based, and bacteria-based alternative proteins or proteins from other sources.

This review provides novel insights into the barriers and facilitators operating in different types of built food environments that may affect the uptake of novel foods developed with alternative proteins. Barriers and facilitators may refer to the physical characteristics of the structure, food presentation practices, organizational strategies or policies operating in the setting, the actions and beliefs of retailers or consumers while selling or purchasing the APF in the setting, etc. Our results indicate that perceived and actual availability are common facilitators operating across the various types of built environments. The results also indicated several determinants associated with consumers' choices in specific types of built food environments: the ways food is presented in produce sections (supermarkets), consumers’ green and specialty shopping routines (groceries), a mismatch between retailers’ actions of making APF available in one type of environment (e-commerce), and consumers’ preferences for other types of APF environments (supermarkets, groceries). We also indicate that one type of barrier/facilitator operating within a specific type of built food environment may have different associations with consumers’ choices depending on the type of APF (e.g., social norms regarding masculinity as a barrier for plant-based, but not insect-based, APF in restaurants).

Availability of data and materials

All data analyzed during this study are either secondary (retrieved from original studies included in the review) or included in this published article (and its supplementary information files).

Abbreviations

Alternative protein foods

References marked with an asterisk indicate studies included in the systematic review.

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HZ, AL, EK, MS, ZS, AB, FG, PC, BTN, TP, AS, AX, AK: design of the theoretical construction of the review as well as the searching strategy process; HZ, EK, MS, AL, ZS, AB, PC, TP: screening of potentially relevant documents; HZ, AL: data extraction; EK, MS, ZS, AB: data extraction verification; AB, MS, AL, PC, TP: quality and risk of bias assessment; AL, HZ: data analysis; HZ, AL: writing the manuscript draft; EK, MS, ZS, AB, FG, PC, BTN, TP, AS, AX, AK: critical revision of the intellectual content of the manuscript. All authors read and approved the final manuscript.

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Additional file 1: Description of data: The full list of keywords applied in the review; details of data analysis and synthesis; definitions, theoretical background, and categories applied during the coding procedures; description of the included studies; populations’ characteristics in the included studies; Supplementary Table 1 - descriptive information about the original research included into the review

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Additional file 2: Description of data: Details of the quality and risk of bias assessment of the included in the systematic review studies

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Zaleskiewicz, H., Kulis, E., Siwa, M. et al. Characteristics of built food environments associated with alternative protein food choices: a systematic review. Int J Behav Nutr Phys Act 21 , 58 (2024). https://doi.org/10.1186/s12966-024-01606-6

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Buried or exposed Kirschner wire for the management of hand and forearm fractures: A systematic review, meta-analysis, and meta-regression

Roles Conceptualization, Data curation, Formal analysis, Funding acquisition, Investigation, Methodology, Project administration, Supervision, Writing – original draft, Writing – review & editing

Affiliation Department of Orthopaedics and Traumatology, Faculty of Medicine Universitas Padjadjaran, Bandung, Indonesia

Roles Conceptualization, Data curation, Funding acquisition, Resources, Software, Writing – original draft, Writing – review & editing

Roles Conceptualization, Funding acquisition, Methodology, Project administration, Visualization, Writing – original draft, Writing – review & editing

Roles Formal analysis, Investigation, Methodology, Writing – original draft, Writing – review & editing

Affiliation Department of Medicine, Faculty of Medicine, Universitas Diponegoro, Semarang, Indonesia

Roles Data curation, Formal analysis, Investigation, Methodology, Project administration, Resources, Software, Writing – original draft, Writing – review & editing

* E-mail: [email protected]

Nucki Nursjamsi Hidajat,
R. M. Satrio Nugroho Magetsari,
Gregorius Thomas Prasetiyo,
Danendra Rakha Putra Respati,
Kevin Christian Tjandra

Published: May 15, 2024
https://doi.org/10.1371/journal.pone.0296149
Reader Comments

The recommendation on whether to bury or expose the Kirschner wire (K-wire) for the management of fractures has still been controversial with inconsistent results in the published studies due to the potential issue associated with exposed K-wire is the heightened risk of infection, as it comes into direct contact with the external environment and air. This study aims to summarize the specific outcomes between buried and exposed K-wire for the management of hand and forearm fractures.

We conducted relevant literature searches on Europe PMC, Medline, Scopus, and Cochrane Library databases using specific keywords. This investigation focuses on individuals of any age diagnosed with hand or forearm fractures who underwent surgery involving Kirschner wire (K-wire) fixation. It examines the comparison between buried and exposed K-wire fixation, emphasizing primary outcome pin infection, along with secondary outcomes such as early pin removal, days to pin removal, and surgical duration. The study includes observational studies (cohort/case-control) or randomized clinical trials (RCTs). The results of continuous variables were pooled into the standardized mean difference (SMD), while dichotomous variables were pooled into odds ratio (OR) along with 95% confidence intervals using random-effect models. The quality of included studies was assessed with Cochrane Collaborations, Risk of Bias version 2 (RoB v2).

A total of 11 studies were included. Our pooled analysis revealed that buried K-wire was associated with a lower risk of pin site infection [RR 0.49 (95% CI 0.36–0.67), p < 0.00001, I 2 = 0%] and 33.85 days longer duration until pin removal [MD 33.85 days (95% CI 18.68–49.02), p < 0.0001, I 2 = 99%] when compared with exposed K-wire. However, the duration of surgery was 9.98 minutes significantly longer in the buried K-wire [MD 6.98 minutes (95% CI 2.19–11.76), p = 0.004, I 2 = 42%] with no significant difference in the early pin removal rate [RR 0.73 (95% CI 0.36–1.45), p = 0.37, I 2 = 0%]. Further regression analysis revealed that sample size, age, sex, and duration of follow-up did not affect those relationships.

Buried K-wire may offer benefits in reducing the infection rate with a longer duration until pin removal. However, further RCTs with larger sample sizes are still needed to confirm the results of our study.

Citation: Hidajat NN, Magetsari RMSN, Prasetiyo GT, Respati DRP, Tjandra KC (2024) Buried or exposed Kirschner wire for the management of hand and forearm fractures: A systematic review, meta-analysis, and meta-regression. PLoS ONE 19(5): e0296149. https://doi.org/10.1371/journal.pone.0296149

Editor: Ismail Tawfeek Abdelaziz Badr, Menoufia University, EGYPT

Received: December 4, 2023; Accepted: April 13, 2024; Published: May 15, 2024

Copyright: © 2024 Hidajat et al. This is an open access article distributed under the terms of the Creative Commons Attribution License , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Data Availability: Mendeley Data: Buried or Exposed Kirschner Wire for the Management of Hand and Forearm Fractures: A Systematic Review, Meta-Analysis, and Meta-Regression. DOI: 10.17632/cxjd9nmx8r.1 .

Funding: The author(s) received no specific funding for this work.

Competing interests: The authors have declared that no competing interests exist.

Introduction

Hand and forearm fractures present substantial challenges in orthopedic surgery, impacting infection prevention and postoperative quality of life. The choice of whether to bury or expose Kirschner wires (K-wires), commonly used for fixation, is a critical decision in surgical management of hand and forearm fractures. This decision can influence infection risk, timing of pin removal, and overall surgical outcomes.

Forearm fractures involving the radius and ulna are the most common fracture of the upper limb with an annual incidence of 16.2 fractures per 10,000 individuals, followed by hand fractures involving the metacarpals and phalanx with an annual incidence of 12.5 and 6.4 fractures per 10,000 individuals, respectively [ 1 , 2 ]. Both forearms and hands are essential in carrying out daily activities so these two types of fractures often result in the disruption of a person’s quality of life [ 2 ].

Kirschner wire (K-wire) is often used by orthopedic surgeons, especially those specializing in the field of hand and upper extremity surgery to provide fixation for unstable hand or forearm fractures because it is associated with good outcomes at a relatively low cost [ 3 , 4 ]. Results from several previous studies have demonstrated the non-inferiority of K-wire when compared to plate-screw fixation in the management of unstable metacarpal and phalangeal fractures [ 5 , 6 ]. A meta-analysis study involving 5 randomized clinical trials (RCTs) and 9 cohort studies showed similar clinical, functional, and radiological outcomes between percutaneous K-wires when compared with volar locking plates (VLPs) for distal radius fixation, but with lower re-operation risk in the K-wire group [ 7 ]. These wires can be implanted under the skin or left exposed. A national survey conducted in the United Kingdom (UK) showed that the majority of orthopedic surgeons, plastic surgeons, and junior surgical trainees chose to leave K-wire exposed because it was easier to remove [ 8 ]. The concern that may arise from exposed K-wire is the potentially greater risk of infection because it has direct contact with the outside air and environmental exposure [ 8 ].

Several studies have been conducted to compare buried and exposed K-wires in the management of hand and forearm fractures but have yielded inconsistent results due to high risk of infection [ 9 , 10 ]. The gap in existing reviews becomes apparent as these studies do not offer a cohesive and thorough comprehension of the effectiveness and risks associated with exposed versus buried K-wires. Furthermore, the current reviews lack a comparison regarding pin removal, surgery duration, and regression analysis concerning sample size, age, sex, and duration of follow-up regarding the management of hand and forearm fractures using buried versus exposed Kirschner wires. The reported inconsistencies stem from variations in the types of fractures studied, the populations involved, or the specific outcomes considered. This systematic review and meta-analysis aim to fill this gap by encompassing a broad spectrum of studies that explore the specific outcome of exposed and buried K-wires in the management of hand and forearm fractures.

The significance of this review lies in its commitment to summarizing the latest evidence and offering an up-to-date and thorough analysis. By addressing the existing inconsistencies in the literature, the review strives to bring clarity and consensus to the comparative effectiveness and risks associated with exposed and buried K-wires. Furthermore, the review seeks to inform clinical practice by providing valuable insights that can guide orthopedic surgeons and practitioners in making informed decisions regarding the optimal approach for managing hand and forearm fractures.

Material and method

Eligibility criteria.

This review was written according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement and Cochrane Handbook guidelines [ 11 , 12 ]. We included the following studies: (1) studies on patients of any age with the diagnosis of hand (phalangeal or metacarpal) or forearm (radius or ulna) fractures who have undergone surgery with Kirschner wire (K-wire) fixation (Population); (2) compare between buried and exposed K-wire fixation (Intervention and Control); (3) have data on the primary outcome (pin infection) with/without secondary outcomes (early pin removal, days to pin removal, and duration of surgery) (Outcome); (4) presented in the form of observational studies (cohort/case-control) or randomized clinical trials (RCTs) (Study Design).

Meanwhile, the studies (1) conducted in patients with humeral, shoulder, or lower extremity fractures; (2) using another method of fixation besides K-wire for the patients; (3) presented in the form of case reports, case series, and review articles were excluded from our analysis.

Literature search and study selection

The search of English literature on 4 international databases: Medline, Scopus, Europe PMC, and Cochrane Library was performed by five independent authors from April 28 th , 2023 until March 7 th ,2023. We used the following combined keywords to capture all potentially eligible literature: “(buried OR implanted OR concealed OR embedded) AND (exposed OR uncovered) AND (Kirschner wire OR K-wire) AND (hand fractures OR phalangeal fractures OR metacarpal fractures OR forearm fractures OR radius fractures OR ulna fractures)” as shown in Table 1 . At first, the identified articles from those databases were removed for duplicates and then screened based on their titles/abstracts. These articles that passed the initial screening process underwent the second step of evaluation in the form of full-text to see their compatibility with our inclusion/exclusion criteria. All of these processes for article selection were conducted by the same five authors who performed the literature searching process. All discrepancies were resolved through discussion with all of the authors. If the decision did not happen, the corresponding author took the final decision based on the determination of the eligibility and desired outcomes of the studies.

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https://doi.org/10.1371/journal.pone.0296149.t001

Data extraction

We extracted the following data for analytical purposes: study ID, publication year, country, study design, sample size, baseline characteristics of participants (mean age and sex distribution), follow-up duration, the number of participants in the buried and exposed K-wire groups, and the outcomes of interest. These data extracted by five independent authors were tabulated into Microsoft Excel 2019.

The outcomes of interest in this study were divided into primary and secondary outcomes. The primary outcome was pin site infection which encompassed both superficial and deep infection at or around the site of K-wire placement. The secondary outcomes consisted of early pin removal rate, days to pin removal, and duration of surgery. Early pin removal was defined as the removal of K-wire before the initially planned date due to complications.

Risk of bias assessment

The risk of bias assessment was conducted by five independent authors using validated tools. For analyzing the quality of included RCTs, we used a tool from Cochrane Collaborations, namely Risk of Bias version 2 (RoB v2), which includes a methodological assessment of 5 domains: (a) randomization process; (b) deviations from intended interventions; (c) missing outcome data; (d) measurement of the outcome; and (e) selection of the reported results [ 13 ]. The result is shown in Fig 2 . The authors’ evaluations were categorized as "low risk," "high risk," or "some concerns" of bias [ 13 ]. For analyzing the quality of included cohort/case-control studies, we used Newcastle-Ottawa Scale (NOS) from the Ottawa Hospital Research Institute (OHRI) which includes 3 domains of assessment: (1) selection of participants; (2) comparability between exposed and non-exposed cohort; and (3) outcome ascertainment [ 14 ]. The total score that can be achieved ranged from 0 to 9 where articles with ≥7 scores were considered as having "good" qualities [ 14 ].

Statistical analysis

We used mean difference (SMD) along with 95% confidence intervals (95% CI) for the analytical pooling of continuous variables outcomes by using the Inverse-Variance formula. We also pooled dichotomous variable outcomes into risk ratio (RR) along with 95% CI by using the Mantel-Haenszel formula. Random-effect models were chosen in this review because of the consideration that significant heterogeneity was expected due to differences in the population characteristics and differences in the duration of follow-up. In this review, we used the I-squared (I 2 ) statistic to assess the heterogeneity between studies where I 2 values of >50% were categorized as significant heterogeneity. We used a combined formula from Luo D et al. [ 15 ] and Wan X et al. [ 16 ] to change the data expressed in the form of the median and interquartile range (IQR) or data expressed as median, minimum, and maximum into mean and standard deviations (SD) for pooled analysis purposes. A publication bias analysis was performed when there were more than 10 studies on each outcome of interest. If an asymmetry in the funnel plot was found, we intended to review the PICO and outcomes characteristics to determine whether the observed asymmetry could be attributed to publication bias or alternative factors such as methodological heterogeneity among the studies. All of these statistical analyses were carried out using an application from the Cochrane Collaboration, namely Review Manager 5.4. The robustness of the outcomes was scrutinized through sensitivity meta-analysis, wherein only studies with overall low risk of bias included.

The statistical methodology of regression analysis is frequently employed for data analysis to elucidate the association between a dependent variable and one or more independent variables. Utilizing linear regression, the model centers on the dependent variable, such as sample size, age, sex, and follow-up duration, and whether they exhibited influence the observed associations or not. The choice of these variables is guided by theoretical considerations and their relevance to the analytical objectives. The regression analysis is conducted using STATA 17 for robust data interpretation.

Study selection and characteristics

A literature search on 4 international databases yielded a total of 166 studies. After removing duplicates and screening studies based on their titles and abstracts, 140 studies were removed, leaving 26 studies. These 26 studies were assessed in a full-text form where 15 studies did not meet our eligibility criteria as follows: 8 studies were conducted on patients with humeral fractures, 2 studies did not have any control group, 2 studies did not have data on the outcome of interest, 1 study was only review article, 1 study did not use K-wire for all of the participants, and 1 study was not published in the English language, thus only 11 studies [ 9 , 10 , 17 – 25 ] were included in the final analysis Fig 1 . Of these 11 studies, 5 were prospective RCTs and 6 were retrospective cohort studies. The number of samples ranged from 52 to 695 with the duration of follow-up varying from 6 weeks to 1 year. A summary of the baseline characteristics of the included studies can be found in Table 2 .

https://doi.org/10.1371/journal.pone.0296149.g001

https://doi.org/10.1371/journal.pone.0296149.t002

Quality of study assessment

The risk of bias assessment by using the RoB v2 tool revealed that only 1 RCT [ 9 ] had a "low risk" of bias in all five assessment domains. The remaining four RCTs [ 10 , 17 – 19 ] were judged to have “some concern” risk of bias. One RCT [ 18 ] used consecutive non-random sampling for the selection of participants which was deemed an inappropriate method for randomization, but there was no significant difference in the baseline characteristics of participants in the two groups of intervention, suggesting no serious problems during randomization, therefore was judged to have “some concern” risk of bias in the randomization process. Two RCTs [ 10 , 17 ] did not mention in detail the blinding of the outcome assessors, therefore were judged to have “some concern” risk of bias in the measurement of the outcome. Lastly, one remaining RCT [ 19 ] did not mention in detail regarding both the randomization method and "blinding" of the outcome assessors, therefore were also judged to have "some concern" risk of bias in the randomization process and measurement of the outcome. The evaluation of all included cohort studies by using the NOS tool revealed "good quality" studies with total scores ranging from 7 to 8. The summary of the risk of bias assessment for all included studies in this review can be found in Fig 2 and Table 3 .

https://doi.org/10.1371/journal.pone.0296149.g002

https://doi.org/10.1371/journal.pone.0296149.t003

Data synthesis

Primary outcome..

Pin site infection . Based on our pooled analysis of 11 studies (n = 2,022), it has been shown that buried K-wire was associated with a lower risk of pin site infection when compared with exposed K-wire in patients with hand and forearm fractures [RR 0.49 (95% CI 0.36–0.67), p < 0.00001, I 2 = 0%, random-effect models] as shown in Fig 3 . Subgroup analysis based on the study design revealed consistent and significant results for both RCTs [RR 0.38 (95% CI 0.21–0.68), p = 0.001, I 2 = 0%, random-effect models] and observational studies [RR 0.54 (95% CI 0.37–0.79), p = 0.001, I 2 = 0%, random-effect models] with a lower RR was found in the RCTs studies.

https://doi.org/10.1371/journal.pone.0296149.g003

Secondary outcome.

Early pin removal . Pooled analysis from 6 studies (n = 1,200) showed a non-significant difference in the rate of early pin removal between buried and exposed K-wire for patients with hand and forearm fractures [RR 0.73 (95% CI 0.36–1.45), p = 0.37, I 2 = 0%, random-effect models] as in Fig 4 . Subgroup analysis based on the study design revealed that the results remained non-significant for both RCT [RR 0.65 (95% CI 0.10–4.03), p = 0.64, I 2 = 31%, random-effect models] and observational studies [RR 0.74 (95% CI 0.34–1.61), p = 0.44, I 2 = 0%, random-effect models].

https://doi.org/10.1371/journal.pone.0296149.g004

Days to pin removal . Pooled analysis from 4 studies (n = 1,493) showed that buried K-wire was associated with significantly longer days to pin removal when compared to exposed K-wire in patients with hand and forearm fractures [MD 33.85 days (95% CI 18.68–49.02), p < 0.0001, I 2 = 99%, random-effect models]. The forest plot is available in Fig 5 Subgroup analysis based on the study design revealed significant results for both RCT [MD 29.00 (95% CI 24.04–33.96), p < 0.00001, random-effect models] and observational studies [MD 32.53 (95% CI 16.89–48.18), p < 0.0001, I 2 = 99%, random-effect models] with the MD was found to be higher in the observational studies.

https://doi.org/10.1371/journal.pone.0296149.g005

Duration of surgery . Pooled analysis from 3 studies (n = 325) showed that the duration of surgery was significantly longer for the buried K-wire when compared to exposed K-wire in patients with hand and forearm fractures [MD 6.98 minutes (95% CI 2.19–11.76), p = 0.004, I 2 = 42%, random-effect models] as shown in Fig 6 . Subgroup analysis based on the study design revealed that a significant difference in the duration of surgery was only seen in the RCTs studies [MD 7.53 (95% CI 0.74–14.31), p = 0.03, I 2 = 70%, random-effect models] but not in the observational studies [MD 5.45 minutes (95% CI -5.14–16.04), p = 0.31, random-effect models].

https://doi.org/10.1371/journal.pone.0296149.g006

Meta-regression . Identification of risk factors that influence the relationship of buried and exposed K-wire with all of the outcomes of interest was done with meta-regression. Our meta-regression revealed that variability in those outcomes in hand and forearm fractures patients receiving buried or exposed K-wire fixation cannot be explained by known patient factors associated with predictors of treatment outcomes ( Table 4 ). From our meta-regression analysis, it was revealed that pin site infection in hand or forearm fractures patients treated with either buried or exposed K-wire was not significantly influenced by sample size ( p = 0.3469) ( Fig 7A ), age ( p = 0.5300) ( Fig 7B ), sex ( p = 0.1105) ( Fig 7C ), or follow-up duration ( p = 0.2895) ( Fig 7D ).

Meta-regression analysis showed that the comparison between buried and exposed K-wire with the pin site infection outcome was not significantly affected by sample size (A), age (B), sex (C), nor follow-up duration (D).

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The association between either buried or exposed K-wire with early pin removal was not significantly influenced by sample size ( p = 0.8827) ( Fig 8A ), age ( p = 0.4780) ( Fig 8B ), sex ( p = 0.5103) ( Fig 8C ), or follow-up duration ( p = 0.2063) ( Fig 8D ).

Meta-regression analysis showed that the comparison between buried and exposed K- wire with the early pin removal outcome was not significantly affected by sample size (A), age (B), sex (C), nor follow-up duration (D).

https://doi.org/10.1371/journal.pone.0296149.g008

Our meta-regression analysis also revealed that the days to pin removal in patients with hand or forearm fractures receiving either buried or exposed K-wire were not significantly influenced by sample size ( p = 0.1839) ( Fig 9A ), age ( p = 0.0514) ( Fig 9B ), or sex ( p = 0.8928) ( Fig 9C ). Variable "follow-up duration" was not possible to be included in the meta-regression analysis for this outcome because of the insufficient number of data in the included studies.

Meta-regression analysis showed that the comparison between buried and exposed K- wire with the days to pin removal outcome was not significantly affected by sample size (A), age (B), sex (C).

https://doi.org/10.1371/journal.pone.0296149.g009

Finally, the outcome "duration of surgery" was also not possible to be analyzed in the meta-regression analysis due to the insufficient number of included studies for this outcome.

All the meta-regression results for each outcome of interest is summarized in this below Table 4 .

Publication bias.

The Funnel-plot analysis shown in Fig 10 for the pin site infection outcome revealed a relatively symmetrical inverted plot, suggesting no indication of publication bias. Meanwhile, the publication bias analysis was not performed for the early pin removal, days to pin removal, and duration of surgery outcomes due to less than 10 studies included in these outcomes where funnel plots and statistical tests to detect publication bias are less reliable [ 26 , 27 ].

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In a randomized controlled trial conducted by Maradei-Pereira JAR et al., the prevailing literature concerning forearm fractures, particularly those implicating the radius and ulna, has underscored their prevalence and consequential implications on routine activities. Kirschner wires (K-wires) have arisen as a prevalent fixation modality, notably within the domain of hand and upper extremity surgery, attributed to their favorable outcomes and cost-effectiveness [ 9 ]. Nonetheless, previous investigations comparing K-wires against alternative fixation techniques have yielded disparate results, with specific scrutiny directed towards the potential risk of infection posed by exposed K-wires [ 9 , 10 ].

Based on the results of our meta-analysis, it has been shown that buried K-wire was associated with a lower risk of pin site infection and longer duration of pin removal when compared with exposed K-wire in patients with hand and forearm fractures, although the early pin removal rate did not differ significantly between two groups and the duration of surgery was significantly longer in the buried K-wire group. Importantly, to provide a comprehensive assessment of the practical implications, we scrutinized that re-surgical intervention was required for the removal of buried K-wires. This additional consideration is crucial for understanding the postoperative management and potential complications associated with buried K-wire fixation. Despite the longer duration of surgery observed in the buried K-wire group, the lack of a significant difference in the early pin removal rate suggests that the benefits associated with buried K-wire placement outweigh the potential drawbacks. Further regression analysis also revealed that the study’s variables, such as sample size, age, sex, and follow-up duration did not significantly influence these relationships.

The results of our meta-analysis were in line with the results of the previous study by Chen L et al. [ 28 ] which also showed that buried K-wires had a lower risk of infection compared to exposed K-wires even though early pin removal did not differ significantly between groups. However, there were some differences between our current meta-analysis and the previous study by Chen L et al. [ 28 ].

First, the previous study by Chen L et al. [ 28 ]. only included a total of 7 studies consisting of 2 RCTs and 5 observational studies. Meanwhile, our current meta-analysis has included more studies, a total of 11 studies (5 RCTs and 6 observational studies) with an additional 3 RCTs and 1 observational study when compared to the previous study which will certainly produce more solid evidence.

Second, the previous study by Chen L et al. [ 28 ]. combined the results from RCT studies with results from observational studies. This action was inappropriate and not recommended when we referred to the guidelines from the Cochrane Handbook of Systematic Reviews of Intervention [ 12 ]. Observational studies tend to be susceptible to several biases such as selection bias and information bias which can have an impact on the research results [ 29 , 30 ]. Selection bias can lead to differences in the baseline characteristics of the two groups of participants which will also influence the results of the analysis [ 29 , 30 ]. Information bias can lead to inaccuracies of data and the results of outcome measurement obtained [ 29 , 30 ]. In addition, observational studies are often unable to anticipate the existence of several confounders which can also have an impact on research results [ 29 , 30 ]. Meanwhile, RCTs can avoid the presence of confounders through a process of randomizing the participants [ 31 , 32 ]. The existence of bias such as selection bias and information bias can also be minimized by allocation concealment and blinding methods, both for the participants and the outcome assessors [ 31 , 32 ]. Therefore, it is advisable to separate the results from RCTs and the results from observational studies. In our current meta-analysis, we have followed the recommendations of the Cochrane guidelines by separating the results from the RCTs and observational studies that can be seen in all of our forest plots, although there were no significant differences in results between those two study designs.

Third, our current meta-analysis had an additional outcome in the form of "days to pin removal" which was not analyzed in the previous study by Chen L et al. [ 28 ] From this new outcome, it was found that buried K-wire was able to provide a longer time for pin removal when compared to exposed K-wire. In addition, our current meta-analysis was also equipped with a meta-regression analysis to see the effect of several study variables, such as sample size, age, sex, and follow-up duration. From the results of our regression analysis, we have found no significant effect of these variables on the outcomes of interest.

The results of our meta-analysis align with the findings of previous studies, specifically those conducted by Maradei-Pereira JAR et al. [ 9 ] and Khaled M et al. [ 10 ]. In our analysis, buried K-wires demonstrated a lower risk of pin site infection, consistent with the study on distal radial fractures by Maradei-Pereira JAR et al. [ 9 ], which observed a greater risk of infection when K-wires were left exposed. The contrast in infection risk between exposed and buried K-wires was further supported by our meta-analysis.

Conversely, our results also correspond with the study by Khaled M et al. [ 10 ], which showed no significant difference in the complication rate, including pin infection incidence, between exposed and buried K-wires. The lack of a significant difference in the early pin removal rate between the two groups in our meta-analysis echoes the findings of Khaled M et al. [ 10 ]. The existing literature, combined with our meta-analysis results, suggests a consistent trend in favor of buried K-wires for reducing the risk of pin site infection, while not significantly impacting the early pin removal rate.

Despite having several advantages above, our current meta-analysis is not without limitations. The majority of included studies have small sample sizes, under 100 participants. Some of these studies, especially the RCTs, also have "some concern" risk of bias caused by a lack of detailed information regarding the randomization method and the blinding of the outcome assessors. Two of our outcomes of interest, namely days to pin removal and duration of surgery, have relatively high heterogeneities (above 50%) which may be due to differences in the surgeon’s experience and length of follow-up duration. Finally, data regarding the cost-effectiveness analysis of the two K-wire methods were lacking in the included studies, therefore cannot be analyzed further. Further RCTs with larger sample sizes are still needed to confirm the results of our meta-analysis.

Our systematic review and meta-analysis suggests that buried K-wire may be more beneficial than exposed K-wire to provide a lower risk of infection and longer duration until pin removal in patients with hand and forearm fractures. However, the duration of surgery was relatively longer in the buried K-wire groups with no significant difference in the rate of early pin removal. The final decision on whether to bury or expose the K-wire fixation should still be based on the surgeon’s judgment with the consideration of the patient’s clinical condition as well as the benefits and risks for each patient. Further RCTs with larger sample sizes are still needed to confirm the results of our study.

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Graphene field-effect transistor biosensors for detection of heavy metal ions

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Published: 16 May 2024

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Junhui Du 1 ,
Chuanjin Cui 1 ,
Hongshuo Chen ORCID: orcid.org/0000-0003-3712-6961 1 ,
Haibin Liu 2 ,
Xuechao Zhang 3 &
Wensi Zhang 1

The issue of food safety has received significant attention in recent years. Heavy metal ions in food can accumulate in living organisms and significantly threaten human health. Therefore, it is crucial to detect heavy metal ions. Conventional instrumental analysis methods have high accuracy, but the disadvantage is the high cost and the complexity of the operation process, so it is very urgent to establish a low-cost, rapid, and continuous detection method for heavy metal ions. Field effect transistor (FET) biosensors are one of the most promising detection tools for heavy metal ion detection due to demonstrated advantages of rapidity, accuracy, and continuity in hazard detection. This review first introduces the structure and principle of graphene FETs in detail, then lists some examples of graphene FETs for detecting common heavy metal ions, and analyzes their advantages and disadvantages in depth. Finally, the development direction of graphene FET biosensors in heavy metal ion detection highlighted in this paper.

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Acknowledgements

This work was supported by the project of Youth Fund for Science and Technology Research in Hebei Universities (Grant Number: QN2020194), the project of Tangshan Science and Technology Plan (Grant Number: 22130221G) and the Project of the Youth Fund for National Natural Science Foundation of China (Grant Number: 32001791).

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A systematic review (PROSPERO database preregistration; no. CRD42023388700) was conducted by searching 13 databases for peer-reviewed journals focusing on the fields of economics and business, agriculture, medical sciences, and social sciences. Data searches, coding, and quality evaluations were conducted by at least 2 researchers.
Effect of Probiotic Supplements on the Oral Microbiota—A Narrative Review
Data from systematic reviews and meta-analyses show that probiotics positively impact clinical parameters of oral diseases such as gingivitis, dental caries, and periodontitis. However, the working mechanism of probiotics is not fully understood, but is hypothesized to be mediated by direct and indirect interactions with the oral microbiota and the human host. In the present narrative review ...
Buried or exposed Kirschner wire for the management of hand and forearm
Background The recommendation on whether to bury or expose the Kirschner wire (K-wire) for the management of fractures has still been controversial with inconsistent results in the published studies due to the potential issue associated with exposed K-wire is the heightened risk of infection, as it comes into direct contact with the external environment and air. This study aims to summarize ...
Graphene field-effect transistor biosensors for detection of heavy
This review first introduces the structure and principle of graphene FETs in detail, then lists some examples of graphene FETs for detecting common heavy metal ions, and analyzes their advantages and disadvantages in depth. Finally, the development direction of graphene FET biosensors in heavy metal ion detection highlighted in this paper.

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How to Review a Journal Article

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Evaluating Purpose and Argument

Evaluating the Presentation/Organization of Information

Evaluating Methods

Evaluating Data

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Step 1: Write the Title

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Step 3: Article Identification

Step 4: Introduction

Step 5: Summarize the Article

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