Minimal clinically important difference for time spent in moderate to vigorous physical activities in COPD after pulmonary rehabilitation

Enhancing physical activity (PA) is crucial for COPD management. This study estimated the minimal clinically important difference (MCID) for time spent in moderate to vigorous physical activities per day (MPVA/day) after pulmonary rehabilitation (PR) in people with COPD. This was a secondary analysis of a clinical trial (<ext-link>NCT04223362</ext-link>) and included people with COPD who completed a 12-week community-based PR programme. PA outcomes were collected pre- and post- PR, for 7 days, using ActiGraph GT3X+ (minimum 8h/day for 4 days). The MCID established for steps/day in COPD, set at 600 steps/day, was used as an anchor. Mean change, ROC curves and linear regression were used as anchor-based methods; 0.5*standard deviation, standard error of measurement (SEM), 1.96*SEM and minimal detectable change were used as distribution-based methods. The MCID was pooled by weighting 2/3 to anchor- and 1/3 to distribution-based methods. 51 people with COPD were included (86% male, 71±8 years, 57±17 FEV1%pred). A significant, positive, and moderate correlation (ρ=0.5, P<0.001) was present between changes in steps/day and MVPA/day. The pooled MCID for MVPA/day was 10.5 minutes (Figure 1). An increase of 11 min/day in MVPA post-PR indicates clinically relevant improvements in PA for people with COPD. The established MCID may aid health professionals and policy makers in evaluating PA interventions. <fig><object-id>erj;64/suppl_68/OA3689/F1</object-id><object-id>F1</object-id><object-id>F1</object-id><graphic></graphic></fig>