mMRC (Modified Medical Research Council) Dyspnea Scale
Patients with respiratory diseases, to assess degree of baseline functional disability due to dyspnea.
- The mMRC Dyspnea Scale quantifies disability attributable to breathlessness, and is useful for characterizing baseline dyspnea in patients with respiratory diseases.
- Describes baseline dyspnea, but does not accurately quantify response to treatment of chronic obstructive pulmonary disease (COPD).
- Does not capture patient effort, such that dyspnea from pulmonary disease (and not behavioral responses to disability) are reflected in mMRC Dyspnea Scale scores.
- Does not consistently correlate with spirometric measurements (e.g. FEV₁) for patients with respiratory disease due to COPD.
- Demonstrates at least moderate positive correlation with other dyspnea scores, including the baseline dyspnea index (BDI) and oxygen cost diagram (OCD) (Chhabra 2009).
- At least moderately correlated with healthcare-associated quality of life, particularly for patients with COPD (Henoch 2016).
- Scores are variably associated with patients’ perceptions of respiratory symptom burden or disease severity (Rennard 2002).
- Scores are associated with morbidity (hospitalization and adverse cardiovascular outcomes) and, in some studies, mortality.
- Used as a component of the BODE Index, which predicts adverse outcomes, including mortality and risk of hospitalization (Celli 2004).
- Easy and efficient to calculate.
- Provides a baseline assessment of functional impairment attributable to dyspnea from respiratory disease.
- Correlates with healthcare-associated quality of life, morbidity, and possibly mortality for patients with respiratory diseases (particularly COPD).
- Has been used for almost two decades in multiple different heterogeneous patient populations.
- Correlates with other clinical and research dyspnea indices.
- Inter-rater reliability is very high.
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- The mMRC Dyspnea Scale is best used to establish baseline functional impairment due to dyspnea attributable to respiratory disease; tracking the mMRC over time or with therapeutic interventions is of less certain clinical utility.
- Furthermore, while the mMRC is correlated with morbidity and mortality for patients with respiratory disease, currently-available data do not confirm attributable cause and effect between mMRC Dyspnea Scale scores and patient-centered outcomes.
- While measuring mMRC Dyspnea Scale scores in patients with respiratory disease (particularly COPD) to establish baseline functional dyspnea burden is appropriate, mMRC scores are not independently used in clinical practice to guide clinical management or therapeutic interventions.
- However, the Global Initiative for Obstructive Lung Disease (GOLD) treatment guidelines have, since 2011, included the mMRC as a component of a multi-faceted assessment and treatment approach to patients with COPD.
- A patient’s mMRC Dyspnea Scale score, or another dyspnea measurement, such as the COPD Assessment Test (CAT), is combined with the patient’s FEV₁ percent predicted and the frequency of COPD exacerbations to guide treatment interventions
The mMRC Dyspnea Scale score must be contextualized with an individual patient’s history, physical, and available diagnostic test results. For patients with a higher mMRC grade (e.g. ≥2) and clinical circumstances consistent with respiratory disease, measuring spirometry (e.g., FEV₁ and FVC), determining the patient’s BODE Index and/or GOLD stage, and pursuing further targeted diagnostic and/or therapeutic interventions is appropriate.
Selection of the appropriate grade:
Dyspnea only with strenuous exercise
Dyspnea when hurrying on level ground or walking up a slight hill
Walks slower than people of the same age because of dyspnea, or has to stop for breath when walking at own pace on level ground
Stops for breath after walking 100 yards (91 m) or after a few minutes on level ground
Too dyspneic to leave house or breathless when dressing
Facts & Figures
Higher grade indicates higher severity.
The Medical Research Council (MRC) scale was developed in the 1950s based on questions used by healthcare providers in the Pneumoconiosis Research Unit in Cardiff, Wales, and was first referred to in a manuscript in 1952 (Fletcher 1952). The original MRC scale was developed from these clinical questions and used in numerous research studies over the past 60 years. The MRC was modified in a study in 1988, generating the modified Medical Research Council (mMRC) scale.
The original study of the mMRC involved 161 patients with shortness of breath at a single medical center (Mahler 1988). Of the 161 patients, a diagnosis for their dyspnea could only be determined in 153 patients, who constituted the research cohort. Patients’ mMRC scores were compared to other dyspnea measures (BDI and OCD) and spirometric results (FEV₁, FVC, and maximum inspiratory and expiratory pressures). Inter-rater reliability of the mMRC was 98% in this study, and the mMRC was moderately to strongly correlated with the OCD and BDI indices. mMRC moderately correlated with pulmonary function measurements.
A subsequent validation study of 161 patients at a single outpatient clinic in Japan demonstrated factor grouping of the mMRC with other dyspnea measurements (BDI and OCD) and healthcare related quality of life (Hajiro 1998). Furthermore, mMRC scores moderately to strongly correlated with functional assessments of patients’ cardiopulmonary fitness (including FEV₁, RV/TLC, and VO₂max).
Subsequent single center and small to moderate sized studies, have consistently demonstrated moderate correlations between the mMRC and other dyspnea scores (Chhabra 2009). mMRC scores have been shown to be highly correlated with health care associated quality of life, particularly for patients with COPD (Henoch 2016). However, correlations between mMRC scores and spirometric results, ABG results, or 6 minute walk distance were not noted in some studies, such that the association between mMRC results and functional metrics is uncertain (Chhabra 2009).
Original/Primary ReferenceMahler DA, Wells CK. Evaluation of clinical methods for rating dyspnea. Chest. 1988;93(3):580-6.
ValidationHajiro T, Nishimura K, Tsukino M, Ikeda A, Koyama H, Izumi T. Analysis of clinical methods used to evaluate dyspnea in patients with chronic obstructive pulmonary disease. Am J Respir Crit Care Med. 1998;158(4):1185-9.
Other ReferencesNishiyama O, Taniguchi H, Kondoh Y, et al. A simple assessment of dyspnoea as a prognostic indicator in idiopathic pulmonary fibrosis. Eur Respir J. 2010;36(5):1067-72.Launois C, Barbe C, Bertin E, et al. The modified Medical Research Council scale for the assessment of dyspnea in daily living in obesity: a pilot study. BMC Pulm Med. 2012;12:61.Celli BR, Cote CG, Marin JM, Casanova C, de Oca MM, Mendez RA, et al. The body mass index, airflow obstruction, dyspnea, and exercise capacity index in chronic obstructive pulmonary disease. N Engl J Med. 2004;350:1005–12. Chhabra SK, Gupta AK, Khuma MZ. Evaluation of three scales of dyspnea in chronic obstructive pulmonary disease. Ann Thorac Med. 2009;4(3):128-32.GOLD: Global Initiative for Obstructive Lung Disease Global Strategy for the Diagnosis, Management and Prevention of Chronic Obstructive Pulmonary Disease 2011 Available from: http://www.goldcopd.com Accessed August 2nd, 2017Fletcher CM. Discussion on the diagnosis of pulmonary emphysema. Proc R Soc Med. 1952;45:576-585. Henoch I, Strang S, Löfdahl CG, Ekberg-Jansson A. Health-related quality of life in a nationwide cohort of patients with COPD related to other characteristics. Eur Clin Respir J. 2016;3:31459.Rennard S, Decramer M, Calverley PM, et al. Impact of COPD in North America and Europe in 2000: subjects’ perspective of confronting COPD International Survey. Eur Respir J. 2002;20(4):799–805.
About the Creator
Donald A. Mahler, MD, is a professor emeritus at Geisel School of Medicine at Dartmouth in Hanover, New Hampshire. Clinically, he is a practicing pulmonologist and the director of respiratory services at Valley Regional Hospital in Claremont, NH. Dr. Mahler's research focus is management of COPD.
To view Dr. Donald A. Mahler's publications, visit PubMed
- Jeremy B. Richards, MD