Predictors of changes in 6-min walking distance following pulmonary rehabilitation in COPD patients: a retrospective cohort analysis

Abstract

Introduction: Pulmonary rehabilitation (PR) is recommended to improve the physical and psychological condition of COPD patients. Increased 6-min walking distance (6MWD), is possibly the most significant improvement, given its strong association with physical activity, respiratory function, and health-related quality of life. The aim of this study is to identify predictors of non-response in functional capacity to PR.

Methods: This single center study is a retrospective analysis of data in COPD patients admitted to a PR center (Dieulefit Santé, South Eastern France) between January 2012 and December 2017. Post-PR change in 6MWD was used to determine the functional response to PR. Patients characteristics and pre-PR 6-min walking test responses were analyzed to determine factors associated with post-PR changes in 6MWD.

Results: 835 patients were included. 80% of the patients showed clinically significant 6MWD improvement (≥30 m). The predictors of 6MWD response to PR were age, pre-PR 6MWD, pre-PR end-of-test dyspnea, and long-term oxygen therapy.

An increase of 5 years of age decreased the probability of being a responder by 22%. An increase of 10 m of the pre-PR 6MWD decreased the probability of being a responder by 5%. An increase of 1 unit in pre-PR end-of-test dyspnea decreased the probability of being a responder by 16%. Finally, the need to use oxygen supplementation decreased the probability of being a responder by 70%.

Conclusion: This study identified four important clinical variables predicting a lack of 6MWD response to PR. Patients with such clinical characteristics may require specific PR modalities to improve their functional benefit.