Correlates of Improvement to Pulmonary Rehabilitation in Interstitial Lung Diseases

Introduction: Pulmonary rehabilitation (PR) is beneficial in interstitial lung disease (ILD), but predictors of response remain poorly understood. Oxygen therapy may enhance PR effects by improving oxygen saturation, yet its use at rest has been linked to smaller gains in exercise capacity. We explored which factors are associated with a clinically relevant improvement in functional exercise capacity after PR in ILD. Materials and Methods: We retrospectively retrieved data from 58 ILD patients attending a PR program at the Pulmonary Rehabilitation Center in ULS Santa Maria (July to September 2024). Eligibility criteria included the ability to perform the 6-minute walk test (6MWT), complete records and an adequate time span between evaluations. Data collected included sex, age, smoking history, oxygen use at rest, during activities of daily living (ADL) and sleep, home non-invasive ventilation (NIV), and 6MWT distance before and after PR. Logistic regression was used to examine whether oxygen use during ADL predicted a clinically relevant improvement (≥30m) in 6MWT distance, with sex included as an adjustment factor after univariate screening of other clinical variables. Results: Forty-four patients (age 68.3±12.9 years, 68% males) were eligible. In this cohort, 43% were non-smokers and 36% did home NIV. Patients did oxygen therapy mostly during ADL (66%); 39% used supplemental oxygen at rest and 41% during sleep. Clinically relevant improvement was observed in 36% ILD patients. Neither sex nor ADL oxygen use reached statistical significance as predictors of improvement. However, females showed a trend toward higher odds of improvement (OR=3.7, 95%CI 0.9;14.7, p=0.06). Conclusions: These exploratory findings suggest a potential sex-related difference in response to PR in ILD, warranting confirmation in larger studies. Oxygen use during ADL appears unrelated to improvement and may primarily reflect disease severity rather than responsiveness to PR.