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How to Write Case Reports and Case Series

Ganesan, Prasanth

Department of Medical Oncology, Jawaharlal Institute of Postgraduate Medical Education and Research, Puducherry, India

Address for correspondence: Dr. Prasanth Ganesan, Medical Oncology, 3 rd Floor, SSB, Jawaharlal Institute of Postgraduate Medical Education and Research, Dhanvantari Nagar, Puducherry - 605006, India. E-mail: [email protected]

Received March 13, 2022

Received in revised form April 10, 2022

Accepted April 10, 2022

This is an open access journal, and articles are distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 License, which allows others to remix, tweak, and build upon the work non-commercially, as long as appropriate credit is given and the new creations are licensed under the identical terms.

Case reports are considered the smallest units of descriptive studies. They serve an important function in bringing out information regarding presentation, management, and/or outcomes of rare diseases. They can also be a starting point in understanding unique associations in clinical medicine and can introduce very effective treatment paradigms. Preparing the manuscript for a case report may be the first exposure to scientific writing for a budding clinician/researcher. This manuscript describes the steps of writing a case report and essential considerations when publishing these articles. Individual components of a case report and the “dos and don'ts” while preparing these components are detailed.

INTRODUCTION

A case report describes several aspects of an individual patient's presentation, investigations, management decisions, and/or outcomes. This is a type of observational study and has been described as the smallest publishable unit in medical literature.[ 1 ] A case series involves a group of patients with similar presentations or treatments. In modern medicine [ Figure 1 ], these publications are categorized as the “lowest level of evidence”.[ 2 ] However, they serve several essential functions. For example, there are rare diseases where large, randomized trials, or even observational studies may not be possible. Medical practice, in these conditions, is often guided by well-presented case reports or series. There are situations where a single case report has heralded an important therapy change.[ 3 ] Further, case reports are often a student's first exposure to manuscript writing. Hence, these serve as training for budding scholars to understand scientific writing, learn the process of manuscript submission, and receive and respond to reviewer comments. This article explains the reasons why case reports are published and provides guidance for writing such type of articles.

WHY ARE CASE REPORTS PUBLISHED?

A case report is often published to highlight the rarity of a particular presentation. However, it may be of much more value if it also informs some aspects of management. This could be in the form of rare expressions of a common disease so that clinicians who read will be aware and can consider additional possibilities and differential diagnoses when encountering similar situations. A new form of evaluation of a patient, either to facilitate the diagnostics or to improve understanding of the disease condition, may stimulate a case report. Novel treatments may be tried, and the results might be necessary to disseminate. This may be encountered either in rare diseases or conditions where treatment options are exhausted. Moreover, randomized trials report outcomes of a group and often do not inform about the individual patient. [ Table 1 ] describes a few examples of case reports/case series which have had a remarkable impact on medical practice.

ETHICAL ISSUES

If there is a possibility of patient identification from the report, it is mandatory to obtain informed consent from the patient while approval from the institutional ethics committee (IEC) may also be needed depending on institutional policies.[ 7 ] If identifying information is absent (or if suitable steps are taken to remove identifying information or hide the identity, (such as by covering the eyes), it may still be required by some journals to obtain ethics committee approval for certain types of case reports. If a case series involves retrospective chart review, “waiver-of-consent” may be sought from the ethics committee. Indian Ethical Guidelines do not separately address this issue in case reports.[ 8 ] The Committee on Publication Ethics has described best practices for journals when publishing case reports which also gives links to model consent forms.[ 9 ]

HOW TO START?

If you are a beginner and you have identified an interesting case which you want to report, the first step would be to sit with your team and discuss the aspects of the case you want to highlight in your publication.[ 10 ] Do a literature search and try to summarize available information before writing the draft. It would also be a good idea to understand which journal you are targeting; this will assist in determining the number of figures, the word limits, and ethical requirements (such as informed consent). Discussions with senior faculty about the authors and their order should also be done at this point to avoid issues later. For a beginner, it would be a good practice to present the case in the department or in an institutional scientific forum before writing up the manuscript.

COMPONENTS OF a CASE REPORT

A case report usually has the following sections: an abstract, a brief introduction, the actual description of the case, and finally, the discussion which highlights the uniqueness of the case and includes a conclusion statement. Many journals these days publish case reports only as a letter to editor; in such cases, an abstract is not usually required.

The title must be informative about the problem being reported. It may refer to the particular issue being highlighted in the report, or it may refer to the educational aspect of that particular report. Catchy titles are often used by authors to trigger interest among the readers and make them want to read the article. Authors may remember to use titles which will help people locate the article when searching the literature.

When writing a title, it may be best to avoid terms such as “case report,” “review of literature,” “unique,” “rare,” “first-report”; these do not add value to the presentation.

Introduction

This must introduce the condition and clearly state why the case report is worth reading. It may also contain a brief mention of the current status of the problem being described with supporting references.

Describing the case

The case must be presented succinctly, in a chronological order, clearly highlighting the salient aspects of the case being reported. Relevant negative findings may be provided. For example, if a case is being reported for elaborating a new type of treatment, then more attention must be given to treatment aspects (e.g., name of the drug, dosage, schedule, dose modifications, or the type of surgery, duration, and type of anesthesia) after briefly describing the presentation and diagnostics. The idea is that the reader must be able to apply the treatment in his/her practice if required.

However, if the case is being presented for diagnostic rarity/unusual clinical features/pathological aspects, then more attention must be given to these aspects. For example, if the emphasis is on tissue pathology, then the description must include details about tissue processing, types of stains, and immunohistochemistry details.

Figures and tables

Figures, as in any publication, should be self-explanatory. A properly constructed figure legend can be used for describing certain aspects of the case much better than long-winded text in the main manuscript. This will also help to reduce the word count in the main manuscript. If there are multiple figures (e.g., follow-up radiology series and response to treatment images), these can be combined as [ Figure 1 ]a, [ Figure 1 ]b, [ Figure 1c ] or [ Figure 1 ]a, [ Figure 1 ]b, [ Figure 1 ]c, [ Figure 1d ]. This will help conform to the figure number limits prescribed by the journal. While preparing the figures, one must ensure that the quality of the art/photograph is not compromised. Further, patient identifying features must be masked, unless necessary to show.

Tables are usually not part of case reports but may be used. One example is presenting the baseline investigations in a tabular format which can facilitate assimilation as well as reduce the word count. Tables are more often used in case series. The most common is a type of table where the features of all the cases included are summarized with each row referring to an individual patient. This usually works for a series of up to ten patients; beyond that, the table may become crowded and difficult to understand. Tables may also be used in the discussion section to summarize related, published reports to date.

Discussion including review

A case report may help to alter the approach to patient management in the clinic or it may even stimulate original research evaluating a new treatment. Thus, the discussion must summarize the unique aspects of the case (why is the case different?) and the essential learning points/implications (how will it change management?/What further research needs to be done?). In addition to stating the differences from existing literature, the discussion should also attempt to explain these differences.

If the condition or treatment approach being focused on is sufficiently rare, reviewing all available cases published until that point is critical. This review may be presented in a table with each case described briefly. A more nuanced study might attempt to summarize the relevant demographics and clinical details of the various cases published to date in the form of a table (e.g., median age, gender distribution, and survival outcomes).

CASE SERIES - WHAT IS DIFFERENT?

There is no formal definition as to what is case series and what would be considered a retrospective cohort study. In general, a case series comprises <10 cases; beyond that, it may be feasible to apply formal statistics and may be considered a cohort study.

Both case reports and case series are descriptive studies. Case series must have similar cases and hence the inclusion must be clearly defined. The interventions must be documented in a way that is reproducible and follow-up of each individual in the report must be available. Although formal statistical analyses are usually not a part of case series, authors may attempt to summarize baseline demographic parameters using descriptive statistics.

ABSTRACT OF a CASE REPORT

As explained earlier, a few journals do not require abstracts for case report submissions. When required, one should try to highlight the salient aspects of the case presented and the reason for the publication within the abstract word limit, which may be as short as 100–200 words. Spend time and effort in writing a good abstract as this is a portion which is usually read by the editor during manuscript screening and may have implications for whether the article progresses to the next stage of editorial processing.

REFERENCES IN a CASE REPORT

One may only cite key references in a case report or series as there is limited scope for elaborate literature search. Most journals have a limit of 10–15 references for case reports; when publishing as a letter to editor (or correspondence), the allowed reference limit may be even lower (five or less for some journals).

CHOOSING THE RIGHT JOURNAL

Many journals have recently stopped publishing case reports and series. This is often an attempt by journals to optimize their resources (space and reviewer time) to attain the highest possible impact. Although this is unfortunate, it is a reality which must be acknowledged. Nonetheless, the advent of online-only journals has led to more options for aspiring authors. Some journals accept case series, whereas others have “sister” journals created to accept case reports and other, less definitive, contributions to the literature.[ 11 ] It is an important exercise to study all available journals accepting case reports of the type being written. The case report must be tailored to the journal's requirements. Many journals may charge an article processing fee; author(s) must consider whether they are willing to pay and publish. Some of these may be predatory journals; authors must be wary of them and scrupulously avoid publishing in such journals as they can permanently stain the publication records of a researcher.

PUBLISHING THE CASE REPORT/SERIES AS a LETTER TO EDITOR/IMAGE SERIES

When the matter to be conveyed is very minimal or is being published mainly for its rarity, letters to editor may be an alternate route to publish case report data. Interesting images may be published in the form of “images” series which is now a part of many journals. The flexibility of web-based publishing also allows interesting videos to be published online.

GUIDELINES FOR CASE REPORTS

There are guidelines which help authors in the preparation and submission of case reports. The CAse REports (CARE) checklist is one such popular guideline. It provides a “checklist” and other resources for authors that can help navigate the process of writing a case report, especially when a person is doing it for the first time.[ 12 ]

AUTHORSHIP IN CASE REPORTS

Although there are no separate guidelines for authorship in “case reports,” general authorship rules follow that for any manuscript. “Gift” authorship must be avoided. All authors must have contributed to the creation of the manuscript in addition to being involved in some aspect of care of the patient being reported. Authorship order should be ideally predecided based on mutual consensus.

CONCLUSIONS

A case report is a useful starting point for one's scientific writing career. There are useful online resources which describe the steps for a newbie writer.[ 13 14 ] [ Table 2 ] summarizes the important components to follow and understand when writing case reports. Although many frontline journals have reduced their acceptance of case reports, these publications continue to serve an essential scientific and academic role.

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Conflicts of interest.

There are no conflicts of interest.

Case reports; manuscript writing; case series; references

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Quantitative study designs: Case Studies/ Case Report/ Case Series

Quantitative study designs.

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Case Study / Case Report / Case Series

Some famous examples of case studies are John Martin Marlow’s case study on Phineas Gage (the man who had a railway spike through his head) and Sigmund Freud’s case studies, Little Hans and The Rat Man. Case studies are widely used in psychology to provide insight into unusual conditions.

A case study, also known as a case report, is an in depth or intensive study of a single individual or specific group, while a case series is a grouping of similar case studies / case reports together.

A case study / case report can be used in the following instances:

• where there is atypical or abnormal behaviour or development
• an unexplained outcome to treatment
• an emerging disease or condition

The stages of a Case Study / Case Report / Case Series

Which clinical questions does Case Study / Case Report / Case Series best answer?

Emerging conditions, adverse reactions to treatments, atypical / abnormal behaviour, new programs or methods of treatment – all of these can be answered with case studies /case reports / case series. They are generally descriptive studies based on qualitative data e.g. observations, interviews, questionnaires, diaries, personal notes or clinical notes.

What are the advantages and disadvantages to consider when using Case Studies/ Case Reports and Case Series ?

What are the pitfalls to look for?

One pitfall that has occurred in some case studies is where two common conditions/treatments have been linked together with no comprehensive data backing up the conclusion. A hypothetical example could be where high rates of the common cold were associated with suicide when the cohort also suffered from depression.

Critical appraisal tools 

To assist with critically appraising Case studies / Case reports / Case series there are some tools / checklists you can use.

JBI Critical Appraisal Checklist for Case Series

JBI Critical Appraisal Checklist for Case Reports

Real World Examples

Some Psychology case study / case report / case series examples

Capp, G. (2015). Our community, our schools : A case study of program design for school-based mental health services. Children & Schools, 37(4), 241–248. A pilot program to improve school based mental health services was instigated in one elementary school and one middle / high school. The case study followed the program from development through to implementation, documenting each step of the process.

Cowdrey, F. A. & Walz, L. (2015). Exposure therapy for fear of spiders in an adult with learning disabilities: A case report. British Journal of Learning Disabilities, 43(1), 75–82. One person was studied who had completed a pre- intervention and post- intervention questionnaire. From the results of this data the exposure therapy intervention was found to be effective in reducing the phobia. This case report highlighted a therapy that could be used to assist people with learning disabilities who also suffered from phobias.

Li, H. X., He, L., Zhang, C. C., Eisinger, R., Pan, Y. X., Wang, T., . . . Li, D. Y. (2019). Deep brain stimulation in post‐traumatic dystonia: A case series study. CNS Neuroscience & Therapeutics. 1-8. Five patients were included in the case series, all with the same condition. They all received deep brain stimulation but not in the same area of the brain. Baseline and last follow up visit were assessed with the same rating scale.

References and Further Reading  

Greenhalgh, T. (2014). How to read a paper: the basics of evidence-based medicine. (5th ed.). New York: Wiley.

Heale, R. & Twycross, A. (2018). What is a case study? Evidence Based Nursing, 21(1), 7-8.

Himmelfarb Health Sciences Library. (2019). Study design 101: case report. Retrieved from https://himmelfarb.gwu.edu/tutorials/studydesign101/casereports.cfm

Hoffmann T., Bennett S., Mar C. D. (2017). Evidence-based practice across the health professions. Chatswood, NSW: Elsevier.

Robinson, O. C., & McAdams, D. P. (2015). Four functional roles for case studies in emerging adulthood research. Emerging Adulthood, 3(6), 413-420.

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Methodological quality and synthesis of case series and case reports, mohammad hassan murad.

1 Evidence-Based Practice Center, Mayo Clinic, Rochester, Minnesota, USA

Shahnaz Sultan

2 Division of Gastroenterology, Hepatology, and Nutrition, University of Minnesota, Center for Chronic Diseases Outcomes Research, Minneapolis Veterans Affairs Healthcare System, Minneapolis, Minnesota, USA

Samir Haffar

3 Digestive Center for Diagnosis and Treatment, Damascus, Syrian Arab Republic

Fateh Bazerbachi

4 Department of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota, USA

Case reports and case series are uncontrolled study designs known for increased risk of bias but have profoundly influenced the medical literature and continue to advance our knowledge. In this guide, we present a framework for appraisal, synthesis and application of evidence derived from case reports and case series. We propose a tool to evaluate the methodological quality of case reports and case series based on the domains of selection, ascertainment, causality and reporting and provide signalling questions to aid evidence-based practitioners and systematic reviewers in their assessment. We suggest using evidence derived from case reports and case series to inform decision-making when no other higher level of evidence is available.

In 1904, Dr James Herrick evaluated a 20-year-old patient from Grenada who was studying in Chicago and suffered from anaemia and a multisystem illness. The patient was found to have ‘freakish’ elongated red cells that resembled a crescent or a sickle. Dr Herrick concluded that the red cells were not artefacts because the appearance of the cells was maintained regardless of how the smear slide was prepared. He followed the patient who had subsequently received care from other physicians until 1907 and questioned whether this was syphilis or a parasite from the tropics. Then in 1910, in a published case report, he concluded that this presentation strongly suggested a previously unrecognised change in the composition of the corpuscle itself. 1 Sickle cell disease became a diagnosis thereafter.

Case reports and case series have profoundly influenced the medical literature and continue to advance our knowledge in the present time. In 1985, the American Medical Association reprinted 51 papers from its journal that had significantly changed the science and practice of medicine over the past 150 years, and five of these papers were case reports. 2 However, concerns about weak inferences and the high likelihood of bias associated with such reports have resulted in minimal attention being devoted to developing frameworks for approaching, appraising, synthesising and applying evidence derived from case reports/series. Nevertheless, such observations remain the bread and butter of learning by pattern recognition and integral to advancing medical knowledge.

Guidance on how to write a case report is available (ie, a reporting guideline). The Case Report (CARE) guidelines 3 were developed following a three-phase consensus process and provide a 13-item checklist that can assist researchers in publishing complete and meaningful exposition of medical information. This checklist encourages the explicit presentation of patient information, clinical findings, timeline, diagnostic assessment, therapeutic interventions, follow-up and outcomes. 3 Yet, systematic reviewers appraising the evidence for decision-makers require tools to assess the methodological quality (risk of bias assessment) of this evidence.

In this guide, we present a framework to evaluate the methodological quality of case reports/series and synthesise their results, which is particularly important when conducting a systematic review of a body of evidence that consists primarily of uncontrolled clinical observations.

Definitions

In the biomedical published literature, a case report is the description of the clinical course of one individual, which may include particular exposures, symptoms, signs, interventions or outcomes. A case report is the smallest publishable unit in the literature, whereas case series report aggregates individual cases in one publication. 4

The median number of patients in articles with ‘case series’ in the title was found to be seven (range 1–6432). The median (range) of the number of cases of articles with ‘case report’ as a publication type was four (1–178). 5 Case reports/case series are usually retrospective although can occasionally be prospective, such as the Herrick’s first case report of sickle cell disease. 1 Case reports/series can also define their subject by exposure or outcome (analogous to a cohort study and case–control study). Therefore, a specific number of patients, the temporal direction of follow-up or even the definition by case/exposure are not differentiating characteristics of case report/series. One unique feature, however, is that case report/series are uncontrolled (non-comparative) and have a relatively small number of individuals.

If a case series is prospective, differentiating it from a single-arm uncontrolled cohort study becomes difficult. In one clinical practice guideline, it was proposed that studies without internal comparisons can be labelled as case series unless they explicitly report having a protocol before commencement of data collection, a definition of inclusion and exclusion criteria, a standardised follow-up and clear reporting of the number of excluded patients and those lost to follow-up. 6

Evaluating methodological quality

Pierson 7 provided an approach to evaluate the validity of a case report based on five components: documentation, uniqueness, objectivity, interpretation and educational value, resulting in a score with a maximum of 10 (a score above 5 was suggested indicate a valid case report). This approach, however, was rarely used in subsequent work and seems to conflate methodological quality with other constructs. For case reports of adverse drug reactions, other systems classify an association as definite, probable, possible or doubtful based on leading questions. 8 9 These questions are derived from the causality criteria that was established in 1965 by the English epidemiologist Bradford Hills. 10 Lastly, we have adapted the Newcastle Ottawa scale 11 for cohort and case–control studies by removing items that relate to comparability and adjustment (which are not relevant to non-comparative studies) and retained items that focused on selection, representativeness of cases and ascertainment of outcomes and exposure. This tool was applied in several published systematic reviews with good inter-rater agreement. 12–16

Proposed tool

The previous criteria from Pierson, 7 Bradford Hills 10 and Newcastle Ottawa scale modifications 11 converge into eight items that can be categorised into four domains: selection, ascertainment, causality and reporting. The eight items with leading explanatory questions are summarised in table 1 .

Tool for evaluating the methodological quality of case reports and case series

Questions 4, 5 and 6 are mostly relevant to cases of adverse drug events.

For example, a study that explicitly describes all the cases who have presented to a medical centre over a certain period of time would satisfy the selection domain. In contrast, a study that reports on several individuals with unclear selection approach leaves the reader with uncertainty to whether this is the whole experience of the researchers and suggests possible selection bias. For the domain of ascertainment, self-report (of the exposure or the outcome) is less reliable than ascertainment using administrative and billing codes, which in turn is less reliable than clinical records. For the domain of causality, we would have stronger inference in a case report of an adverse drug reaction that has resolved with cessation of the drug and reoccurred after reintroduction of the drug. Lastly, for the domain of reporting, a case report that is described with sufficient details may allow readers to apply the evidence derived from the report in their practice. On the other hand, an inadequately reported case will likely be unhelpful in the course of clinical care.

We suggest using this tool in systematic reviews of case reports/series. One option to summarise the results of this tool is to sum the scores of the eight binary responses into an aggregate score. A better option is not to use an aggregate score because numeric representation of methodological quality may not be appropriate when one or two questions are deemed most critical to the validity of a report (compared with other questions). Therefore, we suggest making an overall judgement about methodological quality based on the questions deemed most critical in the specific clinical scenario.

Synthesis of case reports/series

A single patient case report does not allow the estimation of an effect size and would only provide descriptive or narrative results. Case series of more than one patient may allow narrative or quantitative synthesis.

Narrative synthesis

A systematic review of the cases with the rare syndrome of lipodystrophy was able to suggest core and supportive clinical features and narratively summarised data on available treatment approaches. 17 Another systematic review of 172 cases of the infrequently encountered glycogenic hepatopathy was able to characterise for the first time patterns of liver enzymes and hepatic injury in this disease. 18

Quantitative synthesis

Quantitative analysis of non-comparative series does not produce relative association measures such as ORs or relative risks but can provide estimates of prevalence or event rates in the form of a proportion (with associated precision). Proportions can be pooled using fixed or random effects models by means of the various available meta-analysis software. For example, a meta-analysis of case series of patients presenting with aortic transection showed that mortality was significantly lower in patients who underwent endovascular repair, followed by open repair and non-operative management (9%, 19% and 46%, respectively, P<0.01). 19

A common challenge, however, occurs when proportions are too large or too small (close to 0 or to 1). In this situation, the variance of the proportion becomes very small leading to an inappropriately large weight in meta-analysis. One way to overcome this challenge is to transform prevalence to a variable that is not constrained to the 0–1 range and has approximately normal distribution, conduct the meta-analysis and then transform the estimate back to a proportion. 20 This is done using logit transformation or using the Freeman-Tukey double arcsine transformation, 21 with the latter being often preferred. 20

Another type of quantitative analysis that may be utilised is regression. A meta-analysis of 47 published cases of hypocalcaemia and cardiac dysfunction used univariate linear regression analysis to demonstrate that both QT interval and left ventricular ejection fraction were significantly correlated with corrected total serum calcium level. 22 Meta-regression, which is a regression in which the unit of analysis is a study, not a patient, can also be used to synthesise case series and control for study-level confounders. A meta-regression analysis of uncontrolled series of patients with uveal melanoma treated with proton beam therapy has shown that this treatment was associated with better outcomes than brachytherapy. 23 It is very important, however, to recognise that meta-regression results can be severely affected by ecological bias.

From evidence to decision

Several authors have described various important reasons to publish case reports/series ( table 2 ). 7 24 25

Role of case reports/series in the medical literature

It is paramount to recognise that a systematic review and meta-analysis of case reports/series should not be placed at the top of the hierarchy in a pyramid that depicts validity. 26 The certainty of evidence derived from a meta-analysis is contingent on the design of included studies, their risk of bias, as well as other factors such as imprecision, indirectness, inconsistency and likelihood of publication bias. 27 Commonly, certainty in evidence derived from case series/reports will be very low. Nevertheless, inferences from such reports can be used for decision-making. In the example of case series of aortic transection showing lower mortality with endovascular repair, a guideline recommendation was made stating ‘We suggest that endovascular repair be performed preferentially over open surgical repair or non-operative management’. This was graded as a weak recommendation based on low certainty evidence. 28 The strength of this recommendation acknowledged that the recommendation might not universally apply to everyone and that variability in decision-making was expected. The certainty in evidence rating of this recommendation implied that future research would likely yield different results that may change the recommendation. 28

The Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach clearly separates the certainty of evidence from the strength of recommendation. This separation allows decision-making based on lower levels of evidence. For example, despite low certainty evidence (derived from case series) regarding the association between aspirin and Reye’s syndrome in febrile children, a strong recommendation for using acetaminophen over aspirin is possible. 29 GRADE literature also describes five paradigmatic situations in which a strong recommendation can be made based on low quality evidence. 30 One of which is when the condition is life threatening. An example of which would be using hyperbaric oxygen therapy for purpura fulminans, which is only based on case reports. 31

Guideline developers and decision-makers often struggle when dealing with case reports/case series. On occasions, they ignore such evidence and focus the scope of guidelines on areas with higher quality evidence. Sometimes they label recommendations based on case reports as expert opinion. 32 We propose an approach to evaluate the methodological quality of case reports/series based on the domains of selection, ascertainment, causality and reporting and provide signalling questions to aid evidence-based practitioners and systematic reviewers in their assessment. We suggest the incorporation of case reports/series in decision-making based on the GRADE approach when no other higher level of evidence is available.

In this guide, we have made the case for publishing case reports/series and proposed synthesis of their results in systematic reviews to facilitate using this evidence in decision-making. We have proposed a tool that can be used to evaluate the methodological quality in systematic reviews that examine case reports and case series.

Contributors: MHM drafted the paper and all coauthors critically revised the manuscript. All the authors contributed to conceive the idea and approved the final submitted version.

Competing interests: None declared.

Provenance and peer review: Not commissioned; externally peer reviewed.

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A critical guide to case series reports

• PMID: 12897483
• DOI: 10.1097/01.BRS.0000083174.84050.E5

Objective: Provide guidance to investigators and authors regarding appropriate conduct and reporting of case-series studies.

Summary of background data: Evidence-based practice has provided a substantial contribution to advancing clinical science. Many study designs have been critically examined, and the quality of the research literature has improved. A common study design in musculoskeletal medicine is the case series: a description of the course of patients over time. Case series can provide valuable information as to: case definition, trend analyses regarding outcomes, and clues as to causation. Case series cannot be used to draw inferences regarding treatment effect.

Methods: Examination of previous work on identification of characteristics of high quality study designs such as cohort studies; extending this work to case series.

Results: We identified draft characteristics that good case series studies should address: clearly defined study question; well- described study population; well-described intervention; use of validated outcome measures; appropriate statistical analyses; well-described results; discussion/conclusions supported by the data presented; funding sources acknowledged.

Conclusions: We propose these measures to authors and journal editors as one mechanism to improve the quality of the case series study.

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• Carbapenems as Antidotes for the Management of Acute Valproic Acid Poisoning. Perković Vukčević N, Mijatović Jovin V, Vuković Ercegović G, Antunović M, Kelečević I, Živanović D, Vučinić S. Perković Vukčević N, et al. Pharmaceuticals (Basel). 2024 Feb 17;17(2):257. doi: 10.3390/ph17020257. Pharmaceuticals (Basel). 2024. PMID: 38399472 Free PMC article.
• Sequential or Combination Treatments as Rescue Therapies in Immunocompromised Patients with Persistent SARS-CoV-2 Infection in the Omicron Era: A Case Series. Longo BM, Venuti F, Gaviraghi A, Lupia T, Ranzani FA, Pepe A, Ponzetta L, Vita D, Allice T, Gregorc V, Frascione PMM, De Rosa FG, Calcagno A, Bonora S. Longo BM, et al. Antibiotics (Basel). 2023 Sep 19;12(9):1460. doi: 10.3390/antibiotics12091460. Antibiotics (Basel). 2023. PMID: 37760757 Free PMC article.
• The Impact of Medical Nutrition Intervention on the Management of Hyperphosphatemia in Hemodialysis Patients with Stage 5 Chronic Kidney Disease: A Case Series. Moroșan E, Popovici V, Elian V, Dărăban AM, Rusu AI, Licu M, Mititelu M, Karampelas O. Moroșan E, et al. Int J Environ Res Public Health. 2023 Mar 13;20(6):5049. doi: 10.3390/ijerph20065049. Int J Environ Res Public Health. 2023. PMID: 36981958 Free PMC article.
• Treatment Outcomes of Diabetic Patients With Erectile Dysfunction Prescribed High-Dose Tadalafil. Condina A, Lykina T. Condina A, et al. Cureus. 2023 Feb 9;15(2):e34812. doi: 10.7759/cureus.34812. eCollection 2023 Feb. Cureus. 2023. PMID: 36915849 Free PMC article.
• The effect of antenatal corticosteroid use on offspring cardiovascular function: A systematic review. Sacco A, Cornish EF, Marlow N, David AL, Giussani DA. Sacco A, et al. BJOG. 2023 Mar;130(4):325-333. doi: 10.1111/1471-0528.17316. Epub 2022 Oct 27. BJOG. 2023. PMID: 36209465 Free PMC article. Review.

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