Six-Minute Walking Distance Improvement after Pulmonary Rehabilitation Is Associated with Baseline Lung Function in Complex COPD Patients: A Retrospective Study

Introduction. Conflicting results have been so far reported about baseline lung function, as predicting factor of pulmonary rehabilitation (PR) efficacy. Aim. To ascertain whether or not baseline lung function could predict a benefit in terms of a significant change in 6-min walk test (6MWT) after PR. Methods. Seventy-five stable moderate-to-severe COPD inpatients with comorbidities (complex COPD), allocated to a three-week PR program, were retrospectively evaluated. Pulmonary function, 6MWT, dyspnea (BDI/TDI), and quality of life (EQ-VAS) were assessed before and after PR program. The patients were divided into two groups depending on the change in 6MWT (responders > 30 m and nonresponders ≤ 30 m). Logistic regression analysis was used. Results. After PR, 6MWT performance all outcome measures significantly improved (P < 0.01). Compared to nonresponders (N = 38), the responders (N = 37) had lower values in baseline lung function (P < 0.01). Logistic regression analysis showed that FEV(1) < 50% pred and TL, CO < 50% pred were independent predictors of PR efficacy. Conclusions. Our study shows that in stable moderate-to-severe complex COPD inpatients, baseline lung function may predict the response to PR in terms of 6MWT. We also found that complex COPD patients with poor lung function get more benefit from PR.