Pulmonary rehabilitation and functional independence: Impact on survival in patients with fibrotic interstitial lung disease or chronic obstructive pulmonary disease

Background: Pulmonary rehabilitation (PR) aims to improve patients' functioning in interstitial lung disease (ILD) and chronic obstructive pulmonary disease (COPD). The impact of change in functional independence during PR on subsequent survival has not been established. We aimed to determine functional independence during PR and its association with survival over three years post-PR. Methods: This retrospective cohort study included patients with fibrotic ILD or COPD who participated in a 3week inpatient PR program. The Functional Independence Measure (FIM) was assessed at PR entry and discharge. Correlations between FIM and demographics, clinical/functional parameters were analyzed. Time from PR to death/lung transplantation/censoring was assessed, stratified by baseline/changes in FIM above/ below the median. Multivariable Cox proportional hazard models were used to determine the impact of FIM on mortality risk. Results: 223 patients (76 ILD/147 COPD) were included. Mean +/- standard deviation (SD) age was 69 +/- 10 for ILD and 67 +/- 10 for COPD. FIM total and motor scores improved significantly in both groups. Baseline FIM showed a strong negative and change in 6-min walk distance (6MWD) a strong positive correlation with change in FIM during PR. Each 1-point increase in FIM motor score was associated with a 3 % lower risk of mortality (HR 0.97, 95%CI 0.94-1, p = 0.03). Conclusions: Inpatient PR improves functional independence in patients with fibrotic ILD or COPD, and baseline and change in FIM are associated with survival up to three years post-PR. This emphasizes the importance of PR for all patients with chronic lung disease regardless of their initial level of independence.