Factors Associated with 6-Minute Walk Distance Improvement During Outpatient Pulmonary Rehabilitation After Lung Transplantation

RATIONALE: Pulmonary rehabilitation (PR) is recommended after lung transplantation to optimize recovery. Prior studies have evaluated intensive or specialized PR protocols rather than the 36-session comprehensive outpatient model specified by Medicare. OBJECTIVES: We evaluated 6-minute walk distance (6MWD) improvement and factors associated with rehabilitation response in a Medicare PR program. METHODS: We conducted a pragmatic cohort study of 367 lung transplant recipients participating in PR from 2013-2025. The primary outcome was 6MWD. Registry data were linked to obtain pre-transplant demographic, clinical and functional data. Factors associated with 6MWD improvement were evaluated through multivariable regression, inverse probability weighting and machine learning models. RESULTS: Among 367 lung transplant recipients, 286 (78%) completed discharge assessments with median 6MWD improvement of 171 meters (m, 61% relative improvement). Baseline functional capacity was inversely associated with 6MWD improvement (-0.6m per 1m baseline increase [95% CI, -0.7 to -0.5]). Female sex (-44.2m [-64.0 to -24.3]), longer hospital stay (-0.7m/day [-1.3 to -0.1]), and higher BMI (-3.2m per kg/m² [-5.5 to -1.0]) were associated with less improvement. Higher baseline depression scores were paradoxically associated with greater gains (2.4m/PHQ-9 point [0.04 to 4.67], p < 0.05). Neither pre-transplant disease severity (Lung Allocation Score, p = 0.68) nor functional status at transplant (p = 0.33) was associated with rehabilitation response. CONCLUSIONS: In this analysis of outpatient PR linked to transplant registry data, lung transplant recipients achieved substantial functional improvements. Post-transplant baseline function was inversely associated with gains while pre-transplant disease severity showed no significant association, suggesting removal of ventilatory constraints creates relatively uniform rehabilitation potential. These findings support the real-world effectiveness of the Medicare outpatient PR model.