Agreement of the mMRC and NYHA scales for assessing the impact of self-rated breathlessness in cardiopulmonary disease

Functional impact of breathlessness is assessed using the modified Medical Research Council (mMRC) scale in chronic respiratory disease and with the New York Heart Association Functional Classification (NYHA) scale in heart failure. We evaluated agreement between the scales and their concurrent validity with other clinically relevant patient-reported outcomes in cardiorespiratory disease.Outpatients with stable chronic respiratory disease or heart failure were recruited. Agreement between mMRC and NYHA was analysed using Cramer's V and Kendall's Tau B. Concurrent validity was evaluated using correlations with clinically relevant measures of breathlessness, anxiety, depression and health-related quality of life. Analyses were conducted in all participants and separately in chronic obstructive pulmonary disease (COPD) and heart failure.In a total of 182 participants with cardiorespiratory disease, agreement between mMRC and NYHA was moderate (Cramer's V: 0.46; Kendall's Tau B: 0.57,) with similar results in COPD (Cramer's V: 0.46; Kendall's Tau B: 0.66) and in heart failure (Cramer's V: 0.46; Kendall's Tau B: 0.67). In the total population, the scales correlated in similar ways to the other patient-reported outcomes.In outpatients with cardiorespiratory disease, the mMRC and NYHA scales show moderate to strong correlations and similar associations with other patient-reported outcomes. This supports that the scales are comparable when assessing the impact of breathlessness on function and patient-reported outcomes.