modified medical research council dyspnoea scale

MRC Dyspnoea Scale

The mMRC (Modified Medical Research Council) Dyspnoea Scale is used to assess the degree of baseline functional disability due to dyspnoea.

It is useful in characterising baseline dyspnoea in patients with respiratory disease such as COPD. Whilst it moderately correlates with other healthcare-associated morbidity, mortality and quality of life scales (particularly in COPD) the scores are only variably associated with patients' perceptions of respiratory symptom burden. It is used as a component of the BODE Index, which predicts adverse outcomes, including mortality and risk of hospitalisation. The scale is easy and efficient to use.

The mMRC breathlessness scale ranges from grade 0 to 4. It is very similar to the original version and is now widely used in studies. It should be noted that the MRC clearly states on its website that it is unable to give permission for use of any modified version of the scale (including therefore, the mMRC scale). Use of the MRC questionnaire is free but should be acknowledged.

The modified MRC was developed by D A Mahler, see  https://pubmed.ncbi.nlm.nih.gov/3342669/

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MedicalCRITERIA.com

Unifying concepts, modified medical research council (mmrc) dyspnea scale.

The modified Medical Research Council (mMRC) scale is recommended for conducting assessments of dyspnea and disability and functions as an indicator of exacerbation.

The modified Medical Research Council (mMRC) scale

An mMRC scale grade of 3 have a significantly poorer prognosis and that the mMRC scale can be used to predict hospitalization and exacerbation.

References:

• Natori H, Kawayama T, Suetomo M, Kinoshita T, Matsuoka M, Matsunaga K, Okamoto M, Hoshino T. Evaluation of the Modified Medical Research Council Dyspnea Scale for Predicting Hospitalization and Exacerbation in Japanese Patients with Chronic Obstructive Pulmonary Disease. Intern Med. 2016;55(1):15-24. [Medline]
• Launois C, Barbe C, Bertin E, Nardi J, Perotin JM, Dury S, Lebargy F, Deslee G. The modified Medical Research Council scale for the assessment of dyspnea in daily living in obesity: a pilot study. BMC Pulm Med. 2012 Oct 1;12:61. [Medline]

Created Feb 10, 2021.

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Measuring Shortness of Breath (Dyspnea) in COPD

How the Perception of Disability Directs Treatment

Dyspnea is the medical term used to describe shortness of breath, a symptom considered central to all forms of chronic obstructive pulmonary disease (COPD) including emphysema and chronic bronchitis.

As COPD is both a progressive and non-reversible, the severity of dyspnea plays a key role in determining both the stage of the disease and the appropriate medical treatment.

Challenges in Diagnosis

From a clinical standpoint, the challenge of diagnosing dyspnea is that it is very subjective. While spirometry tests (which measures lung capacity) and pulse oximetry (which measures oxygen levels in the blood) may show that two people have the same level of breathing impairment, one may feel completely winded after activity while the other may be just fine.

Ultimately, a person's perception of dyspnea is important as it helps ensure the person is neither undertreated nor overtreated and that the prescribed therapy, when needed, will improve the person's quality of life rather than take from it.  

To this end, pulmonologists will use a tool called the modified Medical Research Council (mMRC) dyspnea scale to establish how much an individual's shortness of breath causes real-world disability.

How the Assessment Is Performed

The process of measuring dyspnea is similar to tests used to measure pain perception in persons with chronic pain. Rather than defining dyspnea in terms of lung capacity, the mMRC scale will rate the sensation of dyspnea as the person perceives it.

The severity of dyspnea is rated on a scale of 0 to 4, the value of which will direct both the diagnosis and treatment plan.

Role of the MMRC Dyspnea Scale

The mMRC dyspnea scale has proven valuable in the field of pulmonology as it affords doctors and researchers the mean to:

• Assess the effectiveness of treatment on an individual basis
• Compare the effectiveness of a treatment within a population
• Predict survival times and rates

From a clinical viewpoint, the mMRC scale correlates fairly well to such objective measures as pulmonary function tests and walk tests . Moreover, the values tend to be stable over time, meaning that they are far less prone to subjective variability that one might assume.  

Using the BODE Index to Predict Survival

The mMRC dyspnea scale is used to calculate the BODE index , a tool which helps estimate the survival times of people living with COPD.

The BODE Index is comprised of a person's body mass index ("B"), airway obstruction ("O"), dyspnea ("D"), and exercise tolerance ("E"). Each of these components is graded on a scale of either 0 to 1 or 0 to 3, the numbers of which are then tabulated for a final value.

The final value—ranging from as low as 0 to as high as 10—provides doctors a percentage of how likely a person is to survive for four years. The final BODE tabulation is described as follows:

• 0 to 2 points: 80 percent likelihood of survival
• 3 to 4 points: 67 percent likelihood of survival
• 5 of 6 points: 57 percent likelihood of survival
• 7 to 10 points: 18 percent likelihood of survival

The BODE values, whether large or small, are not set in stone. Changes to lifestyle and improved treatment adherence can improve long-term outcomes, sometimes dramatically. These include things like quitting smoking , improving your diet  and engaging in appropriate exercise to improve your respiratory capacity.

In the end, the numbers are simply a snapshot of current health, not a prediction of your mortality. Ultimately, the lifestyle choices you make can play a significant role in determining whether the odds are against you or in your favor.

Janssens T, De peuter S, Stans L, et al. Dyspnea perception in COPD: association between anxiety, dyspnea-related fear, and dyspnea in a pulmonary rehabilitation program . Chest. 2011;140(3):618-625. doi:10.1378/chest.10-3257

Manali ED, Lyberopoulos P, Triantafillidou C, et al. MRC chronic Dyspnea Scale: Relationships with cardiopulmonary exercise testing and 6-minute walk test in idiopathic pulmonary fibrosis patients: a prospective study . BMC Pulm Med . 2010;10:32. doi:10.1186/1471-2466-10-32

Esteban C, Quintana JM, Moraza J, et al. BODE-Index vs HADO-score in chronic obstructive pulmonary disease: Which one to use in general practice? . BMC Med . 2010;8:28. doi:10.1186/1741-7015-8-28

Chhabra, S., Gupta, A., and Khuma, M. " Evaluation of Three Scales of Dyspnea in Chronic Obstructive Pulmonary Disease. " Annals of Thoracic Medicine. 2009; 4(3):128-32. DOI: 10.4103/1817-1737.53351 .

Perez, T.; Burgel, P.; Paillasseur, J.; et al. " Modified Medical Research Council scale vs Baseline Dyspnea Index to Evaluate Dyspnea in Chronic Obstructive Pulmonary Disease. " International Journal of Chronic Obstructive Pulmonary Disease . 2015; 10:1663-72. DOI: 10.2147/COPD.S82408 .

By Deborah Leader, RN  Deborah Leader RN, PHN, is a registered nurse and medical writer who focuses on COPD.

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MRC Dyspnoea Scale - MRC

The MRC Dyspnoea Scale, also called the MRC Breathlessness Scale, has been in use for many years for grading the effect of breathlessness on daily activities. This scale measures perceived respiratory disability, using the World Health Organization (WHO) definition of disability being “any restriction or lack of ability to perform an activity in the manner or within the range considered normal for a human being”.

The MRC Dyspnoea Scale is simple to administer as it allows the patients to indicate the extent to which their breathlessness affects their mobility.

The 1-5 stage scale is used alongside the questionnaire to establish clinical grades of breathlessness.

MRC Breathlessness Scales: 1952 and 1959

Questionnaire on Respiratory Symptoms

The questionnaire was first published in 1960 under the approval of the MRC Committee on the Aetiology of Chronic Bronchitis. This was revised and a new version published in 1966. When the committee disbanded, the responsibility for it was passed to the newly formed MRC Committee for Research into Chronic Bronchitis who again revised it in 1976. When this committee disbanded, the responsibility for the questionnaire passed to the Committee on Environmental and Occupational Health (CEOH) who reviewed it and issued what remains to be the most recent version in 1986.

The Questionnaire on Respiratory Symptoms was designed to be used in large scale epidemiological studies only (100-1,000 people). It cannot be used on an individual basis.

Questionnaire on respiratory symptoms and instructions to interviewers (1966)

Questionnaire on respiratory symptoms and instructions to interviewers (1976)

Questionnaire on respiratory symptoms and instructions to interviewers (1986)

Permission to reuse the MRC Dyspnoea Scale

In accordance with MRC’s Open Access Policy , permission is granted from the MRC to use the MRC Dyspnoea Scale for any purpose (including research and commercial purposes) and MRC hereby agrees not to assert its rights in relation to the proposed use of the MRC Dyspnoea Scale.

You must give appropriate credit (“Used with the permission of the Medical Research Council”) and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests that the MRC endorses you or your use.

We cannot give permission to use any modified versions of this scale including the MRC Scale.

Note: The MRC is not in a position to authorise translations or check back-translations

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Ask a question, or get further information about any of the MRC scales. Email: [email protected]

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The modified Medical Research Council scale for the assessment of dyspnea in daily living in obesity: a pilot study

Claire launois.

1 Service des Maladies Respiratoires, INSERM UMRS 903, Hôpital Maison Blanche, CHU de Reims, 45 rue Cognacq Jay 51092, Reims, Cedex, France

Coralie Barbe

2 Unité d'Aide Méthodologique, Pôle Recherche et Innovations, Hôpital Robert Debré, CHU de Reims, Reims, France

Eric Bertin

3 Service d’Endocrinologie-Diabétologie-Nutrition, Hôpital Robert Debré, CHU de Reims, Reims, France

Julie Nardi

Jeanne-marie perotin, sandra dury, françois lebargy, gaëtan deslee.

Dyspnea is very frequent in obese subjects. However, its assessment is complex in clinical practice. The modified Medical Research Council scale (mMRC scale) is largely used in the assessment of dyspnea in chronic respiratory diseases, but has not been validated in obesity. The objectives of this study were to evaluate the use of the mMRC scale in the assessment of dyspnea in obese subjects and to analyze its relationships with the 6-minute walk test (6MWT), lung function and biological parameters.

Forty-five obese subjects (17 M/28 F, BMI: 43 ± 9 kg/m 2 ) were included in this pilot study. Dyspnea in daily living was evaluated by the mMRC scale and exertional dyspnea was evaluated by the Borg scale after 6MWT. Pulmonary function tests included spirometry, plethysmography, diffusing capacity of carbon monoxide and arterial blood gases. Fasting blood glucose, total cholesterol, triglyceride, N-terminal pro brain natriuretic peptide, C-reactive protein and hemoglobin levels were analyzed.

Eighty-four percent of patients had a mMRC ≥ 1 and 40% a mMRC ≥ 2. Compared to subjects with no dyspnea (mMRC = 0), a mMRC ≥ 1 was associated with a higher BMI (44 ± 9 vs 36 ± 5 kg/m 2 , p = 0.01), and a lower expiratory reserve volume (ERV) (50 ± 31 vs 91 ± 32%, p = 0.004), forced expiratory volume in one second (FEV 1 ) (86 ± 17 vs 101 ± 16%, p = 0.04) and distance covered in 6MWT (401 ± 107 vs 524 ± 72 m, p = 0.007). A mMRC ≥ 2 was associated with a higher Borg score after the 6MWT (4.7 ± 2.5 vs 6.5 ± 1.5, p < 0.05).

This study confirms that dyspnea is very frequent in obese subjects. The differences between the “dyspneic” and the “non dyspneic” groups assessed by the mMRC scale for BMI, ERV, FEV 1 and distance covered in 6MWT suggests that the mMRC scale might be an useful and easy-to-use tool to assess dyspnea in daily living in obese subjects.

Obesity, defined as a Body Mass Index (BMI) greater than or equal to 30 kg/m 2 , is a significant public health concern. According to the World Health Organization, worldwide obesity has more than doubled since 1980 and in 2008 there were about 1.5 billion overweight adults (25 ≤ BMI < 30 kg/m 2 ). Of these, over 200 million men and nearly 300 million women were obese [ 1 ].

Dyspnea is very frequent in obese subjects. In a large epidemiological study, 80% of obese patients reported dyspnea after climbing two flights of stairs [ 2 ]. In a series of patients with morbid obesity, Collet et al. found that patients with a BMI > 49 kg/m 2 had more severe dyspnea assessed with BDI (Baseline Dyspnea Index) than obese patients with a BMI ≤ 49 kg/m 2 [ 3 ]. The most frequent pulmonary function abnormalities associated with obesity [ 4 , 5 ] are a decrease in expiratory reserve volume (ERV) [ 6 - 8 ], functional residual capacity (FRC) [ 6 - 8 ], and an increase in oxygen consumption [ 9 ]. Although the mechanisms of dyspnea in obesity remain unclear, it is moderately correlated with lung function [ 3 , 10 - 16 ]. Of note, type 2 diabetes [ 17 ], insulin resistance [ 18 ] and metabolic syndrome [ 19 ] have been shown to be associated with reduced lung function in obesity. It must be pointed out that dyspnea is a complex subjective sensation which is difficult to assess in clinical practice. However, there is no specific scale to assess dyspnea in daily living in obesity. The modified Medical Research Council (mMRC) scale is the most commonly used validated scale to assess dyspnea in daily living in chronic respiratory diseases [ 20 - 22 ] but has never been assessed in the context of obesity without a coexisting pulmonary disease.

The objectives of this pilot study were to evaluate the use of the mMRC scale in the assessment of dyspnea in obese subjects and to analyze its relationships with the 6-minute walk distance (6MWD), lung function and biological parameters.

Adult obese patients from the Department of Nutrition of the University Hospital of Reims (France) were consecutively referred for a systematic respiratory evaluation without specific reason and considered for inclusion in this study. Inclusion criteria were a BMI ≥ 30 kg/m 2 and an age > 18 year-old. Exclusion criteria were a known coexisting pulmonary or neuromuscular disease or an inability to perform a 6MWT or pulmonary function testing. The study was approved by the Institutional Review Board (IRB) of the University Hospital of Reims, and patient consent was waived.

Clinical characteristics and mMRC scale

Demographic data (age, sex), BMI, comorbidities, treatments and smoking status were systematically recorded. Dyspnea in daily living was evaluated by the mMRC scale which consists in five statements that describe almost the entire range of dyspnea from none (Grade 0) to almost complete incapacity (Grade 4) (Table ​ (Table1 1 ).

The modified Medical Research Council (mMRC) scale

Six-minute walk test

The 6MWT was performed using the methodology specified by the American Thoracic Society (ATS-2002) [ 23 ]. The patients were instructed that the objective was to walk as far as possible during 6 minutes. The 6MWT was performed in a flat, long, covered corridor which was 30 meters long, meter-by-meter marked. Heart rate, oxygen saturation and modified Borg scale assessing subjectively the degree of dyspnea graded from 0 to 10, were collected at the beginning and at the end of the 6MWT. When the test was finished, the distance covered was calculated.

Pulmonary function tests

Pulmonary function tests (PFTs) included forced expiratory volume in one second (FEV 1 ), vital capacity (VC), forced vital capacity (FCV), FEV 1 /VC, functional residual capacity (FRC), expiratory reserve volume (ERV), residual volume (RV), total lung capacity (TLC) and carbon monoxide diffusing capacity of the lung (DLCO) (BodyBox 5500 Medisoft Sorinnes, Belgium). Results were expressed as the percentage of predicted values [ 24 ]. Arterial blood gases were measured in the morning in a sitting position.

Biological parameters

After 12 hours of fasting, blood glucose, glycated hemoglobin (HbAIc), total cholesterol, triglyceride, N-terminal pro brain natriuretic peptide (NT-pro BNP), C-reactive protein (CRP) and hemoglobin levels were measured.

Statistical analysis

Quantitative variables are described as mean ± standard deviation (SD) and qualitative variables as number and percentage. Patients were separated in two groups according to their dyspnea: mMRC = 0 (no dyspnea in daily living) and mMRC ≥ 1 (dyspnea in daily living, ie at least short of breath when hurrying on level ground or walking up a slight hill).

Factors associated with mMRC scale were studied using Wilcoxon, Chi-square or Fisher exact tests. Factors associated with Borg scale were studied using Wilcoxon tests or Pearson’s correlation coefficients. A p value < 0.05 was considered statistically significant. All analysis were performed using SAS version 9.0 (SAS Inc, Cary, NC, USA).

Results and discussion

Demographic characteristics.

Fifty four consecutive patients with a BMI ≥ 30 kg/m 2 were considered for inclusion. Of these, 9 patients were excluded because of an inability to perform the 6MWT related to an osteoarticular disorder (n = 2) or because of a diagnosed respiratory disease (n = 7; 5 asthma, 1 hypersensitivity pneumonia and 1 right pleural effusion).

Results of 45 patients were considered in the final analysis. Demographic characteristics of the patients are presented in Table ​ Table2. 2 . Mean BMI was 43 ± 9 kg/m 2 , with 55% of the patients presenting an extreme obesity (BMI ≥ 40 kg/m 2 , grade 3). Regarding smoking status, 56% of patients were never smokers and 11% were current smokers. The main comorbidities were hypertension (53%), dyslipidemia (40%) and diabetes (36%). Severe obstructive sleep apnea syndrome was present in 16 patients (43%).

Clinical characteristics of the 45 adult obese patients

Data are expressed as mean ± SD or number (%).

Dyspnea assessment by the mMRC scale and 6MWT

Results of dyspnea assessment are presented in Table ​ Table3. 3 . Dyspnea symptom assessed by the mMRC scale was very frequent in obese subjects with 84% (n = 38) of patients with a mMRC scale ≥ 1 and 40% (n = 18) of patients with a mMRC scale ≥ 2 (29% mMRC = 2, 9% mMRC = 3 and 2% mMRC = 4).

Dyspnea assessment of the 45 adult obese patients

mMRC: modified Medical Research Council, 6MWT: six-minute walk test.

The mean distance covered in 6MWT was 420 ± 112 m. Sixteen percent of patients had a decrease > 4% of SpO2 during the 6MWT and one patient had a SpO2 < 90% at the end of the 6MWT (Table ​ (Table4). 4 ). The dyspnea sensation at rest was very slight (Borg = 1 ± 1.5) but severe after exertion (Borg = 5.4 ± 2.4). Fifty-three percent of patients exhibited a Borg scale ≥ 5 after the 6MWT which is considered as severe exertional dyspnea. No complication occurred during the 6MWT. Subjects with a mMRC score ≥ 2 had a higher Borg score after the 6MWT than subjects with a mMRC score < 2 (6.5 ± 1.5 vs 4.7 ± 2.5, p < 0.05).

Functional characteristics of the 45 adult obese patients

FEV 1 : expiratory volume in one second, VC: vital capacity, FRC: functional residual capacity, ERV: expiratory reserve volume, TLC: total lung capacity, DLCO: carbon monoxide diffusing capacity of the lung, pred: predicted value, 6MWT: six-minute walk test.

Lung function tests

Results of spirometry, plethysmography and arterial blood gases are shown in Table ​ Table4. 4 . Overall, the PFTs results remained in the normal range for most of the patients, except for ERV predicted values which were lower (ERV = 56 ± 34%). There were an obstructive ventilatory disorder defined by a FEV 1 /VC < 0.7 in 5 patients (11%) with 5 patients (13%) exhibiting a mMRC ≥ 1, a restrictive ventilatory disorder defined by a TLC < 80% in 5 patients (13%) with 5 patients (16%) exhibiting a mMRC ≥ 1, and a decrease in alveolar diffusion defined by DLCO < 70% in 10 patients (26%) with 9 patients (28%) exhibiting a mMRC ≥ 1. Arterial blood gases at rest were in the normal range with no hypoxemia < 70 mmHg and no significant hypercapnia > 45 mmHg.

Fifteen percent (n = 7) of patients presented anemia. All patients had a hemoglobin level ≥ 11 g/dL. Mean NT pro-BNP was 117 ± 285 pg/mL. Four patients (10%) had a pro-BNP > 300 pg/mL.Forty-five percent of patients had a fasting glucose level > 7 mmol/L, 51% a Hba1c > 6%, 29% a triglyceride level ≥ 1.7 mmol/L, 35% a total cholesterol level > 5.2 mmol/L and 31% a CRP level > 10 mg/L.

Relationships between the mMRC scale and clinical characteristics, PFTs and biological parameters

The comparisons between the mMRC scale and demographic, lung functional and biological parameters are shown in Table ​ Table5. 5 . Subjects in the mMRC ≥ 1 group had a higher BMI (p = 0.01) (Figure ​ (Figure1A), 1 A), lower ERV (p < 0.005) (Figure ​ (Figure1B), 1 B), FEV 1 (p < 0.05), covered distance in 6MWT (p < 0.01) (Figure ​ (Figure1C) 1 C) and Hb level (p < 0.05) than subjects in the mMRC = 0 group. Of note, there was no association between the mMRC scale and age, sex, smoking history, arterial blood gases, metabolic parameters and the apnea/hypopnea index.

Comparisons of patients with mMRC = 0 and patients with mMRC ≥ 1 concerning clinical characteristics, lung function and biological parameters

Data are expressed as number (%) or mean ± SD; *p value < 0.05, **p value < 0.01.

FEV 1 : expiratory volume in one second, pred: predicted value, VC: vital capacity, FRC: functional residual capacity, ERV: expiratory reserve volume, TLC: total lung capacity, DLCO: carbon monoxide diffusing capacity of the lung, NT pro-BNP: N-terminal pro brain natriuretic peptide, CRP: serum C reactive protein, HbA1c: glycated hemoglobin.

Normal biological parameters values were based on the normal values for our laboratory: fasting glucose: 3.3 to 6.1 mmol/L; HbA1c: 4 to 6%; total cholesterol: 3 to 5.2 mmol/L; triglycerides: 0.3 to 1.7 mmol/L; NT-pro BNP < 300 pg/mL; CRP < 10 mg/L. Anemia was defined as hemoglobin level < 13 g/dL in men and 12 g/dL in women.

Differences in Body Mass Index (BMI) (A), Expiratory reserve volume (ERV) (B) and 6-minute walk distance (C) between non-dyspneic (modified Medical Research Council score = 0) and dyspneic (mMRC score ≥ 1) subjects. *p < 0.05, **p < 0.01. A Wilcoxon test was used.

The relationships between the Borg scale after 6MWT and demographic, lung functional and biological parameters were also analysed. The Borg score after 6MWT was correlated with a higher BMI (correlation coefficient = +0.44, p < 0.005) and a lower FEV 1 (correlation coefficient = -0.33, p < 0.05). No relationship was found between the Borg score after 6MWT and ERV or hemoglobin level. The Borg score after 6MWT was correlated with a higher fasting glucose (correlation coefficient = +0.46, p < 0.005) whereas this parameter was not associated with the mMRC scale (data not shown). We found no statistically different change in Borg scale ratings of dyspnea from rest to the end of the 6MWT between the two groups (p = 0.39).

In this study, 45 consecutive obese subjects were specifically assessed for dyspnea in daily living using the mMRC scale. Our study confirms the high prevalence of dyspnea in daily living in obese subjects [ 2 ] with 84% of patients exhibiting a mMRC scale ≥ 1 and 40% a mMRC scale ≥ 2. Interestingly, the presence of dyspnea in daily living (mMRC ≥ 1) was associated with a higher BMI and a lower ERV, FEV 1 , distance covered in 6MWT and hemoglobin level. Furthermore, a mMRC score ≥ 2 in obese subjects was associated with a higher Borg score after the 6MWT (data not shown).

The assessment of dyspnea in clinical practice is difficult. Regarding the mMRC scale, two versions of this scale have been used, one with 5 grades [ 20 ] as used in this study and an other with 6 grades [ 25 ] leading to some confusion. Other scales have been also used to assess dyspnea [ 26 ]. Collet at al. [ 3 ], Ofir et al. [ 11 ] and El-Gamal [ 27 ] et al provided some evidence to support the use of the BDI, Oxygen cost diaphragm (OCD) and Chronic Respiratory Disease Questionnaire (CRQ) to evaluate dyspnea in obesity. El-Gamal et al [ 27 ] demonstated the responsiveness of the CRQ in obesity as they did measurements before and after gastroplaty-induced weight loss within the same subjects. The Baseline Dyspnea Index (BDI) uses five grades (0 to 4) for 3 categories, functional impairment, magnitude of task and magnitude of effort with a total score from 0 to 12 [ 28 ]. The University of California San Diego Shortness of Breath Questionnaire comprises 24 items assessing dyspnea over the previous week [ 29 ]. It must be pointed out that these scores are much more time consuming than the mMRC scale and are difficult to apply in clinical practice.

To our knowledge, the mMRC scale has not been investigated in the assessment of dyspnea in daily living in obese subjects without a coexisting pulmonary disease. The mMRC scale is an unidimensional scale related to activities of daily living which is widely used and well correlated with quality of life in chronic respiratory diseases [ 20 ] such as chronic obstructive pulmonary disease (COPD) [ 21 ] or idiopathic pulmonary fibrosis [ 22 ]. The mMRC scale is easy-to-use and not time consuming, based on five statements describing almost the entire range of dyspnea in daily living. Our study provides evidence for the use of the mMRC scale in the assessment of dyspnea in daily living in obese subjects. Firstly, as expected, our results demonstrate an association between the mMRC scale and the BMI in the comparison between “dyspneic” and “non dyspneic” groups. Secondly, in our between-group comparisons, the mMRC scale was associated with pulmonary functional parameters (lower ERV, FEV 1 and distance walked in 6MWT) which might be involved in dyspnea in obesity. The reduction in ERV is the most frequent functional respiratory abnormality reported in obesity [ 6 - 8 ]. This decrease is correlated exponentially with BMI and is mainly due to the effect of the abdominal contents on diaphragm position [ 30 ]. While the FEV 1 might be slightly reduced in patients with severe obesity, the FEV 1 /VC is preserved as seen in our study [ 31 ]. The determination of the walking distance and the Borg scale using the 6MWT is known to be a simple method to assess the limitations of exercise capacity in chronic respiratory diseases [ 23 ]. Two studies have shown a good reproducibility of this test [ 32 , 33 ] but did not investigate the relationships between the 6MWD and dyspnea in daily living. Our study confirms the feasibility of the 6MWD in clinical practice in obesity and demonstrates an association between covered distance in 6MWT and the presence or the absence of dyspnea in daily living assessed by the mMRC scale. It must be pointed out that the 6MWT is not a standardized exercise stimulus. Exercise testing using cycloergometer or the shuttle walking test could be of interest to determine the relationships between the mMRC scale and a standardize exercise stimulus. In our between-group comparisons, BMI and FEV 1 were associated with the mMRC scale and correlated with the Borg scale after 6MWT. Surprisingly, the ERV was associated with the mMRC scale but not with the Borg scale. Moreover, the fasting glucose was correlated with the Borg scale after 6MWT but not associated with the mMRC scale. Whether these differences are due to a differential involvement of these parameters in dyspnea in daily living and at exercise, or simply related to a low sample size remains to be evaluated.

As type 2 diabetes, insulin resistance, metabolic syndrome [ 17 - 19 ], anemia and cardiac insufficiency have been shown to be associated with lung function and/or dyspnea, we also investigated the relationships between dyspnea in daily living and biological parameters. A mMRC scale ≥ 1 was associated with a lower hemoglobin level. However, all patients had a hemoglobin level > 11 g/dL and the clinical significance of the association between dyspnea in daily living and a mildly lower hemoglobin level has to be interpreted cautiously and remains to be evaluated. Of note, we did not find any associations between the mMRC scale and triglyceride, total cholesterol, fasting glucose, HbA1C, CRP or NT pro-BNP.

The strength of this study includes the assessment of the relationships between the mMRC scale and multidimensional parameters including exertional dyspnea assessed by the Borg score after 6MWT, PFTs and biological parameters. The limitations of this pilot study are as follows. Firstly, the number of patients included is relatively low. This study was monocentric and did not include control groups of overweight and normal weight subjects. Due to the limited number of patients, our study did not allow the analysis sex differences in the perception of dyspnea. Secondly, we did not investigate the relationships between the mMRC scale and other dyspnea scales like the BDI which has been evaluated in obese subjects and demonstrated some correlations with lung function [ 3 ]. Thirdly, it would have been interesting to assess the relationships between the mMRC scale and cardio-vascular, neuromuscular and psycho-emotional parameters which might be involved in dyspnea. Assessing the relationships between health related quality of life and dyspnea would also be useful. Finally, fat distribution (eg Waist circumferences or waist/hip ratios) has not been specifically assessed in our study but might be assessed at contributing factor to dyspnea. Despite these limitations, this pilot study suggests that the mMRC scale might be of value in the assessment of dyspnea in obesity and might be used as a dyspnea scale in further larger multicentric studies. It remains to be seen whether it is sensitive to changes with intervention.

Conclusions

This pilot study investigated the potential use of the mMRC scale in obesity. The differences observed between the “dyspneic” and the “non dyspneic” groups as defined by the mMRC scale with respect to BMI, ERV, FEV 1 and distance covered in 6MWT suggests that the mMRC scale might be an useful and easy-to-use tool to assess dyspnea in daily living in obese subjects.

Abbreviations

BMI: Body Mass Index; mMRC scale: Modified Medical Research Council scale; 6MWT: Six-minute walk test; PFTs: Pulmonary function tests; FEV 1 : Expiratory volume in one second; VC: Vital capacity; FVC: Forced vital capacity; FRC: Functional residual capacity; ERV: Expiratory reserve volume; RV: Residual volume; TLC: Total lung capacity; DLCO: Carbon monoxide diffusing capacity of the lung; HbA1c: Glycated hemoglobin; NT pro-BNP: N-terminal pro brain natriuretic peptide; CRP: Serum C reactive protein.

Competing interests

None of the authors of the present manuscript have a commercial or other association that might pose a conflict of interest.

Authors’ contributions

CL, CB, EB, JN, JMP, SD, FL and GD conceived the study. CL acquired data. CB performed the statistical analysis. CL and GD drafted the manuscript. All authors read and approved the manuscript prior to submission.

Pre-publication history

The pre-publication history for this paper can be accessed here:

http://www.biomedcentral.com/1471-2466/12/61/prepub

Acknowledgements

We thank the personnel of the Department of Nutrition and Pulmonary Medicine of the University Hospital of Reims for the selection and clinical/functional assessment of the patients.

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• Research article
• Open access
• Published: 07 June 2021

Association between body mass index and patient-reported-outcome questionnaire scores (CAT™, ACT™, mMRC dyspnoea scale, IPAQ) in Ukraine, Kazakhstan and Azerbaijan: results of the CORE study

• D. Nugmanova 1 ,
• Y. Feshchenko 2 ,
• L. Iashyna 2 ,
• M. Polianska 2 ,
• K. Malynovska 3 ,
• I. Stafeyeva 1 ,
• J. Makarova   ORCID: orcid.org/0000-0002-1102-7618 4 &
• A. Vasylyev 5  

BMC Pulmonary Medicine volume  21 , Article number:  192 ( 2021 ) Cite this article

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Metrics details

The overweight/obese population (evaluated by a body mass index, BMI) represents a global health problem and contributes to the development of various chronic diseases. In this epidemiological study we evaluated this relationship by analyzing patient-reported questionnaires related to respiratory function, physical activity and BMI.

In 2013–2015, adult residents of selected cities were enrolled to this study in: Ukraine (M/F: 403/561), Kazakhstan (M/F = 348/597) and Azerbaijan (M/F: 389/544). Height was measured using a vertical measuring board, and body weight was measured by using portable digital scales. All participants were interviewed using CAT™, mMRC scale and IPAQ; respondents who also reported wheezing or whistling chest sounds during the previous 12 months additionally ACT™.

45.4% of respondents in Ukraine, 47.6% in Kazakhstan and 54.9% of respondents in Azerbaijan were found to be overweight/obese (BMI ≥ 25 kg/m 2 ). The mean CAT™ total score among this population versus those respondents with a normal weight was 5.2 versus 3.6 (Ukraine, p  < 0.001), 4.2 versus 2.9 (Kazakhstan, p  < 0.001) and 5.9 versus 4.3 (Azerbaijan, p  < 0.001). The number of respondents without airflow limitations (mMRC score 0) among overweight/obese respondents versus normal weight respondents was 298 (68.2%) versus 456 (86.7%) in Ukraine, 261 (58.1%) versus 387 (78.2%) in Kazakhstan and 343 (67.1%) versus 345 (82.3%) in Azerbaijan. The ACT™ total score between overweight/obese respondents and normal weight respondents was not statistically different. IPAQ showed a tendency towards a higher proportion of “low activity” results (compared to “moderate” and “high”) in the overweight/obese subgroup (24.7% vs. 23.8% in Kazakhstan, 18.5% vs. 14.6% in Azerbaijan), and in Ukraine this difference was significant (12.4% vs. 5.2%, p  < 0.001).

CAT™ and mMRC are widely used tools for respiratory function assessment. Despite CAT™ scores being close to a normal value (< 5), the relationship of both CAT™ and mMRC scores with being overweight/obese was demonstrated in the general adult population of three CIS countries. IPAQ may also be a useful instrument for measuring activity level however, more objective studies are required to evaluate the relationship between BMI and physical activity.

Peer Review reports

Obesity is a global health problem around the world and its prevalence has been increasing over several decades. Body mass index (BMI) is a simple index of weight-for-height that is commonly used to classify overweight and obesity in adults. The World Health Organization defines being overweight as a BMI ≥ 25 kg/m 2 and obesity as a BMI ≥ 30 kg/m 2 ) [ 1 ]. In 2016, more than 1.9 billion adults aged 18 years and older were overweight, which amounts to 39% of the adult population; of these over 650 million were obese, amounting to 13% of the adult population [ 1 ]. In 2010, high BMI was ranked sixth in the risk factors for global burden of disease, accounting for almost 3.5 million deaths per year [ 2 ].

It is well established that being overweight or obese can contribute to the development of various chronic diseases including; cardiovascular disease, metabolic syndrome, diabetes, osteoarthritis, and several types of malignancies [ 1 , 3 ]. At the same time, relationship between BMI and chronic respiratory diseases is complex and an object of discussion. Obesity has been found to be strongly linked with respiratory symptoms and diseases including; exertional dyspnea, obstructive sleep apnea syndrome, obesity, hypoventilation syndrome, chronic obstructive pulmonary disease (COPD), asthma, pulmonary embolism, and aspiration pneumonia [ 4 , 5 ]. The abdominal type of obesity can also play a crucial role in the development of lung function impairment and metabolic syndrome [ 6 ]. Some authors [ 7 ] suggest that being overweight or obese could also be a factor leading to misdiagnosis and subsequent overtreatment of COPD.

Furthermore, overweight and obese individuals are more likely to have respiratory symptoms than individuals with a normal BMI, even in the absence of demonstrable lung disease [ 8 ]. Being overweight or obese is also associated with a dose-dependent increase in the odds of asthma incidence in both men and women [ 9 ].

On the other hand, there is an inverse relationship between BMI and forced expiratory volume in one second (FEV 1 ). BMI is also an independent prognostic factor for COPD, with a clear association between a low BMI and increased mortality. Several studies showed that the BMI/airflow obstruction/dyspnea/exercise capacity (BODE) index, a simple multidimensional grading system, is better than FEV 1 at predicting the risk of death from any cause and from respiratory causes among patients with COPD [ 10 , 11 ] Among patients hospitalized due to acute exacerbation of COPD, where low BMI is quite frequent, higher BMI was independently predictive of better long-term survival [ 12 ]. The reasons for this inverse effect include the mechanical effects of truncal obesity and the metabolic effects of adipose tissue [ 3 ].

This study was aimed to evaluate the results of different patient-reported questionnaires related to COPD and asthma (the COPD Assessment Test (CAT™) [ 13 ], the modified Medical Research Council (mMRC) dyspnoea scale [ 14 ], the Asthma Control Test (ACT™) [ 15 ] and the International Physical Activity Questionnaire (IPAQ) [ 16 ]) among the adult population of three Commonwealth of Independent States (CIS) countries, dependent on BMI. This evaluation was part of the cross-sectional CORE study, where the main goal was to assess the point prevalence of COPD, asthma and allergic rhinitis (AR) in these countries [ 17 ].

Study area and population

This cross-sectional epidemiological study was carried out in 2013–2015 across major cities of three countries: Ukraine (Kyiv), Kazakhstan (Almaty) and Azerbaijan (Baku). Data were captured during household visits, as described earlier [ 17 ].

The study enrolled 964 (90.4% of potentially eligible) participants in Ukraine, 945 (85.4% of potentially eligible) participants in Kazakhstan and 933 (96.9% of potentially eligible) participants in Azerbaijan. Inclusion criteria were: adults (≥ 18 years old), ≥ 10 years of residence in the city and written informed consent. People with contraindications to spirometry or bronchodilator administration, or who did not answer the study questionnaire were excluded.

Patient-reported-outcomes questionnaires and BMI measurement

Socio-demographic data were captured from each participant. Height was measured with a vertical measuring board and recorded to the nearest 0.1 cm. Body weight was measured by using portable, strain gauge digital scales and recorded to the nearest 0.1 kg. BMI was calculated during statistical analysis as body weight (kg)/[height (m)] 2 .

During the visit the investigators performed spirometry testing for participants (spirometer: EasyOne™, NDD Medical Technologies, USA, provided by GlaxoSmithKline), without bronchodilator use (pre-dose) and 15–20 min later (post-dose, after inhalation of salbutamol 200–400 mcg (GlaxoSmithKline)). Participants were asked to fill in the ATS Respiratory Symptoms Questionnaire [ 18 ], CAT™ [ 13 ], ACT™ [ 15 ], the Alcohol Intake and Tobacco Smoking Questions and the IPAQ questionnaire [ 16 ]. Dyspnoea was evaluated using the mMRC dyspnoea scale [ 14 ]. These questionnaires are presented in Additional file 1 .

Criteria for COPD diagnosis

Criteria for COPD were predefined by the protocol using a standard spirometric criteria [ 19 ], when FEV 1 (forced expiratory volume in one second): FVC (forced vital capacity) ratio ≥ 0.70 meant the absence of COPD. Study Executive Committee reviewed the quality and results of spirometry. Diagnosis of asthma was based on the Global Initiative for Asthma [ 20 ] Guidelines, using the ATS Respiratory Symptoms Questionnaire [ 18 ]. AR was diagnosed based on the self-reported (as highlighted in the ATS Respiratory Symptoms Questionnaire) presence of watery runny nose symptoms during the last 12 months, either alone or in combination with any of the following: nasal or ocular symptoms, sneezing, nasal obstruction, nasal itching, or conjunctivitis [ 21 , 22 ].

The point prevalence of COPD, asthma and AR, including previously diagnosed and firstly diagnosed cases, was described earlier [ 17 ].

Statistical analysis

For each country, data were analysed using IBM SPSS Statistics software (IBM Corp., USA) version 21.0 and R software version 3.1.2 (R Core Team, Austria). The number of overweight/obese individuals was divided by the total sample and multiplied by 1000, to estimate the point prevalence, together with 95% Clopper–Pearson confidence intervals (CI) [ 23 ]. Comparisons between categorical variables (IPAQ short form activity category) were performed using Chi-square criteria, between numerical variables using the Mann–Whitney test; statistical significant differences were established at p  < 0.05. Missing data points were not imputed.

Sample size justification

The number of subjects was based on precision approach for evaluation of prevalence. Taking into account a design effect of 1.25, expected prevalence of 10% with a half-width of 95% CI ± 3% or prevalence of 15–20% with a half-width of 95% CI ± 4%, sample size of 465 subjects was required. Subsequently, 930 evaluable individuals (465 aged 18–39 years old and 465 aged ≥ 40 years old) in each country had to be included for final analysis.

Patient characteristics

Across three countries the proportion of participating males was slightly lower than females which reflected the census data proportions: 561 (58.2%) females and 403 (41.8%) males in Ukraine; 597 (63.2%) females and 348 (36.8%) males in Kazakhstan; 544 (58.3%) females and 389 (41.7%) males in Azerbaijan. All respondents in Azerbaijan and 99.7% in Ukraine were Caucasians, whereas in Kazakhstan 62.8% were Asians. Mean age of participants was 40.7 years (SD 15.1; 18.0–85.0) in Ukraine, 42.5 years (SD 15.3; 18.0–89.0) in Kazakhstan and 40.7 years (SD 14.8; 18.0–90.0) in Azerbaijan (Table 1 ).

About half of the respondents were overweight (or obese), i.e. BMI > 25 kg/m 2 , with the following distribution between countries: 437 (45.4%) in Ukraine; 449 (47.6%) in Kazakhstan and 511 (54.9%) in Azerbaijan. COPD based on spirometry results was diagnosed in 3.2% of respondents in Ukraine; 3.8% of respondents in Azerbaijan and almost twice as frequently in Kazakhstan at 6.7% of respondents. Moderate stage of COPD (by GOLD classification) was predominant. In male population, the percent of respondents with COPD (post-dose FEV 1 /FVC < 0.7) was higher than in females (Table 1 ). The graphs also show that mean FEV 1 /FVC values in males are lower than in females in Kazakhstan and Azerbaijan (Fig.  1 ). Asthma was diagnosed in 7.4% of respondents in Ukraine, 12.3% in Azerbaijan and 25.5% in Kazakhstan. AR was diagnosed in 4.5%, 8.6% and 9.7% of respondents, correspondingly (Table 1 ).

Bronchodilator response (post-dose FEV 1 /FVC) by sex (left: females, right: males)

Point prevalence of overweight/obesity

Point prevalence of being overweight/obese was similar in Ukraine (453.8 per 1000 persons (95% CI 422.0–485.9)) and Kazakhstan (475.6 per 1000 persons (95% CI 443.4–508.1)) and seemed to be higher in Azerbaijan (549.5 per 1000 persons (95% CI 516.8–581.8)). See Table 2 .

Patient-reported questionnaires

Overweight/obese respondents had higher CAT™ total score compared to normal weight persons. In Ukraine, the mean (± SD) CAT™ total score was 5.2 ± 6.0 (median of 3.0) in overweight/obese respondents versus 3.6 ± 5.0 (median of 2.0) in respondents with normal weight ( p  < 0.001). In Kazakhstan the mean CAT™ total score was 4.2 ± 4.4 (median of 3.0) versus 2.9 ± 4.2 (median of 1.0) ( p  < 0.001) and in Azerbaijan it was 5.9 ± 5.9 (median of 4.0) and 4.3 ± 5.1 (median of 3.0) in respondents who were overweight/obese and normal weight, respectively ( p  < 0.001). See Table 3 .

Similarly to the CAT™, the mMRC dyspnoea scores were different depending on BMI category. In Ukraine, the percent of subjects without airflow limitations (mMRC score 0) was lower among respondents who were overweight/obese compared with participants who were normal weight. The number of respondents with an mMRC score of 0 was 298 (68.2%) among respondents who were overweight/obese and 456 (86.7%) among respondents with a normal weight. In Kazakhstan, 261 (58.1%) overweight/obese and 387 (78.2%) normal weight respondents had mMRC score of 0, and in Azerbaijan 343 (67.1%) overweight/obese and 345 (82.3%) normal weight respondents had mMRC score of 0. Correspondingly, the number of respondents with mild and moderate dyspnoea (mMRC scores 1 and 2) was higher among respondents who were overweight/obese compared with participants with a normal weight. There were significant differences in mMRC score between respondents who were overweight/obese and normal weight across all three countries ( p  < 0.001). See Table 4 .

ACT™ was filled in by any respondents who experienced wheezing or whistling sounds in their chest during the last 12 months. There were no significant differences in the ACT™ total score between respondents who were overweight/obese and normal weight in Ukraine ( p  = 0.800), Kazakhstan ( p  = 0.207) or Azerbaijan ( p  = 0.836). However, as the population size for this group was small, results should be interpreted with caution. See Table 5 .

The IPAQ questionnaire showed that in Ukraine the distribution of categories of physical activity (low/moderate/high) was significantly different between respondents with a normal weight and those who were overweight/obese. Thus, the proportion of respondents with a low activity level was higher among persons who were overweight/obese (12.4%) compared to those with normal weight (5.2%; p  < 0.001). There were no significant differences in the distribution of categories of physical activity in Kazakhstan ( p  = 0.481) as well as in Azerbaijan ( p  = 0.117). Similarly, the MET-min per week parameter for walking was significantly higher among respondents with a normal weight compared to those who were overweight/obese in Ukraine and Azerbaijan. In Ukraine, MET-min per week for walking (mean ± SD) was 2144.3 ± 1609.1 in respondents with normal weight and 1906.6 ± 1501.9 in respondents who were overweight/obese ( p  = 0.031). In Azerbaijan, MET-min per week for walking was 2534.9 ± 1732.9 in respondents with normal weight and 2136.7 ± 1716.1 in respondents wo were overweight/obese ( p  < 0.001). In Kazakhstan, MET-min per week parameters did not significantly differ between respondents who were normal weight and either overweight/obese. See Table 6 .

In our study several important factors related to respiratory function were evaluated among general adults with a normal weight and who were overweight/obese. This also included the impact these factors had on COPD (by CAT™), dyspnoea (by mMRC scale) and physical activity level (by IPAQ).

The relationship of post-bronchodilator FEV 1 /FVC values and BMI differ by country and by sex, which may be explained by variability in occupational preferences of males and females, environmental, geographical, ethnicity and true biological phenomena, along with common risk factors, affecting lung function (smoking, dusty work etc.). The strongest relationship between the post-dose FEV 1 /FVC values and BMI was observed among Azerbaijan population (Figs.  2 , 3 ).

Relationship of post-dose FEV 1 /FVC values versus BMI, in males

Relationship of post-dose FEV 1 /FVC values versus BMI, in females

In Kazakhstan the relationship of post-dose FEV 1 /FVC values versus BMI in both sexes was shifting to the left, indicating to potentially more harmful impact of associated risk factors on lung function. As shown on the Table 1 prevalence of COPD is substantially higher in Kazakhstan compared to other countries (6.7%). Prevalence of COPD in male population is more than 3 times higher to that among female in Kazakhstan. As was reported previously [ 24 , 25 ] COPD diagnosis was associated with individual risk factors as smoking (OR 3.756 (CI 2.156–6.543)  p  < 0.001) and dusty work (OR 2.306 (CI 1.328–4.002)  p  = 0.002), which complements higher prevalence of smoking in Kazakhstan, compared to other countries (Table 1 ). Authors additionally assume other potential harmful factors, adversely impacting lung function, which include relatively poor ecological conditions in the city Almaty, Kazakhstan, caused by heavy air pollution aggravated by high mountains (3000–5000 m) surrounding the city, and little winds with no proximity to large bodies of water.

Despite the mean CAT™ score corresponding to a normal level in healthy non-smokers (< 5), a statistically significant difference was revealed with a higher CAT™ total score observed among respondents who were overweight/obese compared to those with a normal weight across three countries. CAT™ total score ranged between 0 and 27–39, i.e. maximal value corresponded to high and very high impact of COPD. Mean CAT™ total score in overweight/obese respondents in our study (from 4.2 to 5.9) was similar to that reported in the general health population as seen in the BREATHE study assessing the Arabic version (7.0) [ 26 ], the Japanese version of CAT™ (5.8) [ 27 ], and the CAT™ as assessed in Canada (6.0) [ 28 ]. Interestingly, in two cross-sectional studies assessing patients with stable COPD, the relationship between CAT™ score and BMI was not statistically significant [ 29 , 30 ]. In Italy, also no significant correlation was found between the CAT™ score and sex, age, BMI, or the educational level of subjects with COPD with different severities [ 31 ]. As for the differences observed between overweight/obese persons and normal weight adults in the general population obtained from this study, it is doubtful if it could be considered as clinically significant as it was established earlier that the most reliable estimate of the minimum important difference of the CAT™ is 2 points [ 32 ]. However, the differences between the mean values of CAT™ total score in our study were 1.6 in both Ukraine and Azerbaijan and 1.3 in Kazakhstan.

Dyspnea is common in obese subjects. However, its assessment is complex in clinical practice. It is known that mMRC scale is one of the instruments that had been tested and can be recommended for use in people with increased adiposity based on its psychometric properties (reliability (correlations > 0.8)) and concurrent validity (correlation with severity of airways obstruction and walking distance). Other instruments to assess dyspnea include the Visual Analog Scale, Modified Borg Scale, and Baseline Dyspnea Index (BDI) [ 33 , 34 ]. In the CORE study, the results of the mMRC scale in a general adult population confirmed the data obtained in other studies, showing a higher prevalence of dyspnea among persons who were overweight/obese compared to those with a normal weight; the number of "non dyspneic" participants was 68.2% among respondents who were overweight/obese and 86.7% among respondents with normal weight. In the study conducted by Launois et al. [ 35 ], among 45 obese subjects studied, 84% patients had an mMRC score of ≥ 1 and 40% had an mMRC ≥ 2; differences were obtained between the "dyspneic" and the "non dyspneic" groups as assessed by the mMRC scale for BMI, expiratory reserve volume (ERV), FEV 1 and distance covered in 6-min walk test (6MWT) [ 35 ].

As for physical activity, in our study it was shown that BMI had influence over the distribution of categories of physical activity (low/moderate/high) in a general adult population. In Ukraine the rate of inactivity was 12.4% among overweight/obese persons and 5.2% among normal weight persons ( p  < 0.001). In Kazakhstan and Azerbaijan the proportion of persons with inactivity was higher among those who were overweight/obese compared to normal weight persons (24.7% vs. 23.8% in Kazakhstan, 18.5% vs. 14.6% in Azerbaijan), but the differences were not statistically significant.

IPAQ is a widely used instrument to measure physical activity level in the general health population. In a Spanish study among Colombian college students, an excessive weight was observed in 26.47% of the students where an association between physical inactivity (assessed by IPAQ) and excessive weight was observed [ 36 ]. In another study with participation of students from Peru, according to the IPAQ, 53.9% of the participants recorded high levels of physical activity, 35.4% recorded moderate levels, and 10.7%, recorded low levels [ 37 ]. In a large Mexican survey [ 38 ] among adults it was shown that obesity, the 60–69 year age group and high socioeconomic status were related to more frequent physical inactivity; the prevalence of physical inactivity in 2012 was 19.4% (95% CI 18.1, 20.7). In the study of Tehard et al. [ 39 ] among 757 obese subjects, about one third of men and women were classified as insufficiently active by IPAQ. Therefore, the results of our study on the prevalence of inactivity and relationship with high BMI were in line with data obtained in other studies. However, IPAQ assesses physical activity which was self-reported by the CORE study participants. Therefore, obese and overweight persons could have a different meaning of “vigorous” or “moderate” activity than lean and normal weight people. For example, they may walk slower or shorter distances and report these activities as high level in comparison with normal BMI respondents. In the future, studies could include more objective assessment tools (watches/bracelets or other devices, with real time activity monitoring), which would demonstrate better correlation between BMI and physical activity level.

Limitations of the study

This study was well-designed and conducted in a large population, according to an identical protocol in each country. Cross-sectional design allowed capturing data during a single visit. However, the study does have some limitations.

Despite the households were chosen based on two-step cluster randomization, selection bias cannot be fully excluded. Study population was presented by residents of major cities, and this fact limits the extrapolation of the study data to rural population or within a country. Finally, there might be insufficiently valid or missing data, if they were collected from participants’ word.

Conclusions

In conclusion, CAT™ and mMRC are widely used tools for respiratory function assessment. Despite CAT™ scores being close to a normal value (< 5), the relationship of both CAT™ and mMRC scores with being overweight/obese was demonstrated in the general adult population of three CIS countries. IPAQ may also be a useful instrument for measuring activity level however, more objective studies are required to evaluate the relationship between BMI and physical activity.

Availability of data and materials

The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.

Abbreviations

Allergic rhinitis

• Body mass index

COPD assessment test

Confidence interval

Commonwealth of independent states

Chronic obstructive pulmonary disease

Forced expiratory volume in one second

Forced vital capacity

GlaxoSmithKline

Standard deviation

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Acknowledgements

We thank all investigators for their contribution to the study, allowing the first clinical epidemiology research to happen with a high level of integrity and the contract research organisation, Synergy Research Group, which was funded by GSK, performing the study organisation and conduct.

Funding for this study was provided by GSK (GSK Study Number RES116757, GSK study acronym: CORE). GSK was involved in the study design, collection, analysis, and interpretation of the data, in the writing of the report, and in the decision to submit the article for publication. Asthma Control Test™ is a trademark of QualityMetric Incorporated. The modified Medical Research Council dyspnoea scale (mMRC dyspnoea score) is used with the permission of the Medical Research Council. CAT™, COPD Assessment Test and the CAT™ logo are trademarks of the GSK group of companies.

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All listed authors meet the criteria for authorship set forth by the International Committee for Medical Journal Editors. Y. F., L.I., D.N., M.P., A.V., J.M., I.S. and K.M. provided support in the study concept and protocol development, M. P. provided contribution to the independent spirometry quality review and study site staff trainings. National Institute of Phtysiology and Pulmonology named after F.G. Yanovsky National Academy of Medical Science of Ukraine (NIPP), Kiev, Ukraine and Semey State Medical University, Almaty, Kazakhstan provided advisory support to the study. Editorial support in the form of draft outline, editorial suggestions to draft versions of this paper, collating author comments, assembling tables and figures, referencing, and copyediting was provided by Julia She at Synergy Research Group and was funded by GSK.All authors took active part in this study design, acquisition of data, analysis and interpretation of the study data. Authors participated in critical revisions of the manuscript and have approved the article for publication. The authors contributed to manuscript review, applying their clinical, epidemiology, and study design expertise and take responsibility for the integrity of the data and the accuracy of the data analysis. All authors read and approved the final manuscript.

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The study was reviewed and approved by Independent Ethic Committee in Kazakhstan (Central Commission for Ethics at the Ministry of Health of the Republic of Kazakhstan) and by Local Ethic Committees in Kazakhstan, Azerbaijan and Ukraine (Ethic Committee at Semey State Medical University, Almaty, Kazakhstan; Ethic Committee at Scientific Research Institute of Lung Diseases in Baku, Azerbaijan; Commission for Ethics at National Institute of Phthisiology and Pulmonology F.G. Yanovsky of NAMS, Kiev, Ukraine; Commission for Ethics at Center for Primary Health Care #2 of Shevchenko District, Kiev, Ukraine), according to the local legal requirements. Written informed consent was obtained from each participant before any procedures or data collection related to the study.

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Competing interest

The study was sponsored by GlaxoSmithKline (GSK) marketing a number of treatments for COPD, Allergic Rhinitis, and Asthma. D. N., Y. F., L. I., M. P., I. S. report grants from GlaxoSmithKline, during the conduct of the study; personal fees from GlaxoSmithKline, outside the submitted work. K. M.a, J. M., and A. V. are GSK employees and shareholders.

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Additional file 1.

. “Study questionnaires used in the CORE study” contains the description of patient-reported questionnaires used in the CORE study.

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Nugmanova, D., Feshchenko, Y., Iashyna, L. et al. Association between body mass index and patient-reported-outcome questionnaire scores (CAT™, ACT™, mMRC dyspnoea scale, IPAQ) in Ukraine, Kazakhstan and Azerbaijan: results of the CORE study. BMC Pulm Med 21 , 192 (2021). https://doi.org/10.1186/s12890-021-01542-2

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Received : 13 April 2020

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DOI : https://doi.org/10.1186/s12890-021-01542-2

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• COPD assessment test™
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• Asthma control test™
• International physical activity questionnaire

BMC Pulmonary Medicine

ISSN: 1471-2466

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FATIGUE IN PATIENTS WITH LONG COVID

Affiliations.

• 1 1I.M. Sechenov First Moscow State Medical University, Ministry of Health of Russia (Sechenov University), Moscow, Russia.
• 2 2International Association of Clinical Pharmacologists and Pharmacists, Moscow, Russia.
• PMID: 37991964

Purpose of the study - to characterize the metabolomic profile in patients with fatigue developing within the Long COVID, during dynamic observation. 24 patients diagnosed with U09.9 "Condition after COVID-19 unspecified" were included in a prospective study. Patients were recommended to engage in physical activity, which included moderate aerobic activity such as walking for 45 minutes a day, three days a week. Clinical assessment by scales (Modified Medical Research Council dyspnea scale; 6-minute walk test; Multidimensional fatigue inventory scale; Barthel index), and determination of metabolomic parameters were performed on days 1 and 14-18 of the study. During the observation period, lactate, fumaric acid, symmetrical dimethylarginine, asymmetric dimethylarginine remained above the reference values. The level of adipic acid returns to normal values. As a result of performing physical activity, such as walking, results on the Modified Medical Research Council scale dyspnea scale, Multidimensional fatigue inventory scale, 6 Minutes Walking Test and Barthel Index improve (p<0,001). Metabolic profile of patients with Long COVID demonstrates the complex of abnormalities at 60 days after the onset of the disease. These metabolic changes are point to possible therapeutic targets for specific pathogenetic pharmacotherapy.

• COVID-19* / complications
• Fatigue / etiology
• Post-Acute COVID-19 Syndrome*
• Prospective Studies
• Quality of Life