Dyspnea in COPD: beyond the modified Medical Research Council scale

To determine the correlations among various dyspnea scales, spirometric data, exercise tolerance data, and the Body mass index, airway Obstruction, Dyspnea, and Exercise capacity (BODE) index in patients with COPD.

Between March of 2008 and July of 2009, 79 patients with COPD were recruited, and 50 of those patients were included in the study. After being regularly treated with formoterol for one month, the patients completed the modified Medical Research Council (mMRC, dyspnea scale), Baseline Dyspnea Index (BDI), Oxygen Cost Diagram (OCD), and Shortness Of Breath Questionnaire (SOBQ). Subsequently, the patients underwent spirometry and six-minute walk tests (6MWTs), with determination of the six-minute walk distance (6MWD), as well as initial and final SpO2. All patients also completed the Visual Analogue Scale (VAS) and the Borg scale.

The best correlations were between the Borg scale and the VAS (r s = 0.79) and between the BDI and the SOBQ (r s = -0.73). Among the one-dimensional scales (the VAS, mMRC, OCD, and Borg scale), only the VAS correlated with the spirometric parameters, whereas the multidimensional scales BDI and SOBQ did correlate, but poorly. The MRC, BDI, and SOBQ correlated well with 6MWD. Among the spirometric data, inspiratory capacity (IC) and FVC had the strongest correlations with 6MWD. In the multivariate analysis, BDI and IC were selected as the best predictors of 6MWD.

Multidimensional dyspnea scales should be applied in the evaluation of COPD patients.