Six-Minute Walk Distance in Patients With Severe End-Stage COPD ASSOCIATION WITH SURVIVAL AFTER INPATIENT PULMONARY REHABILITATION

PURPOSE: To evaluate the relationship between the 6-minute walk distance (6MWD) and survival in a cohort of patients with severe end-stage chronic obstructive pulmonary disease (COPD) who received inpatient pulmonary rehabilitation (IPR) from 1995 to 2007. METHODS: We retrospectively analyzed 815 patients with severe end-stage COPD who received IPR. 6MWDs before and after IPR (pre-6MWD, post-6MWD) were compared to assess whether 6MWD was significantly changed after IPR. The Kaplan-Meier survival curves were constructed to show the relationship between survival and 6MWD. The age- and or comorbidities-adjusted Cox proportional hazard model was applied to assess association between the survival and the pre-6MWD, post-6MWD, or difference in 6MWD from the pre-6MWD to post-6MWD (Delta 6MWD). RESULTS: Baseline demographics demonstrated a median age 74.0 years, mostly women (60.1%), and white (89.9%) patients with significant comorbid diseases who were most recently hospitalized in acute care facilities (95.1%). IPR significantly increased the 6MWD (mean distance change: 86.4 m; 95% confidence interval [CI], 81.5-91.3 m). Pre-6MWD was not significantly associated with survival. However, post-6MWD was significantly associated with age- and comorbidity-adjusted survival (post-6MWD hazard ratio = 1.336; 95% CI, 1.232-1.449 [post-6MWD x m relative to post-6MWD 2 x m]), and Delta 6MWD was also significantly associated with age-, comorbidities-, and pre-6MWD-adjusted survival (Delta 6MWD hazard ratio = 1.337; 95% CI, 1.227-1.457 [Delta 6MWD x m relative to Delta 6MWD 2 x m]). CONCLUSIONS: In patients with severe end-stage COPD, IPR significantly improved 6MWD, and the post-6MWD and Delta 6MWD were positively associated with the length of survival.