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 (6 MWT) 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, 6 MWT, 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 6 MWT (responders > 30 m and nonresponders ≤ 30 m). Logistic regression analysis was used. Results. After PR, 6 MWT 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 FEV1 < 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 6 MWT. We also found that complex COPD patients with poor lung function get more benefit from PR.