Minimal clinically important difference in barthel index dyspnea in patients with COPD

Background: The Barthel Index dyspnea (BId) is responsive to physiological changes and pulmonary rehabilitation in patients with chronic obstructive pulmonary disease (COPD). However, the minimum clinically important difference (MCID) has not been established yet. Aim: To identify the MCID of BId in patients with COPD stratified according to the presence of chronic respiratory failure (CRF) or not. Materials and Methods: Using the Medical Research Council (MRC) score as an anchor, receiver operating characteristic curves and quantile regression were retrospectively evaluated before and after pulmonary rehabilitation in 2327 patients with COPD (1151 of them with CRF). Results: The median post-rehabilitation changes in BId for all patients were −10 (interquartile range = −17 to −3, p<0.001), correlating significantly with changes in MRC (r = 0.57, 95% CI = 0.53 to 0.59, p<0.001). Comparing different methods of assessment, the MCID ranged from −6.5 to −9 points for patients without and −7.5 to −12 points for patients with CRF. Conclusion: The most conservative estimate of the MCID is −9 points in patients with COPD, without and −12 in those with CRF. This estimate may be useful in the clinical interpretation of data, particularly in response to intervention studies.