The 6 min walking test (6MWT) has been largely studied. Less is, however, known about responders and non-responders to pulmonary rehabilitation (PR) in other meaningful activities. We explored responders and non-responders and the predictors of response to PR in the 1 min sit-to-stand test (1 min STS) and the 6MWT and compared both measures in classifying responders. An observational study was conducted with 121 people with chronic obstructive pulmonary disease (COPD). The functional status was assessed before and after PR. Baseline differences between responders and non-responders were tested with Mann-Whitney U, chi-square, or Fisher exact tests. Predictors were explored with binary logistic regressions. Agreement between both measures was assessed with chi-square, Cohen's kappa, and McNemar tests. There were 54.5% and 57.0% of responders in the 1 min STS and the 6MWT, respectively. The proportion of responders was significantly different (p = 0.048), with a small agreement between the measures (kappa = 0.180; p = 0.048). The baseline 6MWT was the only significant predictor of response in the 6MWT (OR = 0.995; pseudo-r2 = 0.117; p < 0.001). No significant predictors were found for the 1 min STS. A large number of non-responders in terms of functional status exist. The 1 min STS and the 6MWT should not be used interchangeably. Future studies should explore the added benefit of personalizing PR to this outcome and investigate other potential predictors.
Keywords: COPD; functional status; pulmonary rehabilitation; responder analysis.