Characterising Responders and Non-Responders to Pulmonary Rehabilitation in Interstitial Lung Disease

Pulmonary rehabilitation (PR) is an effective intervention for people with interstitial lung disease (ILD), a group of chronic lung disorders characterised by varying degrees of inflammation and fibrosis of the lung parenchyma. Accordingly, PR is consistently recommended across multiple international ILD clinical practice guidelines. Despite these established benefits, a substantial proportion of people with ILD do not achieve clinically meaningful improvements following PR. Clinically meaningful improvement is commonly defined using the minimal important difference (MID), representing the smallest change in an outcome that is perceived as beneficial by patients and associated with meaningful clinical benefit. The reasons why some individuals derive greater benefit from PR than others remain unclear. Baseline physiological characteristics may influence an individual's capacity to respond to PR; however, this has not been explored to date. This study will undertake a secondary analysis of data from two randomised controlled trials involving PR in people with ILD. Participants who participated in PR will be classified as responders (achieving an improvement greater than or equal to the MID in the trial-specific primary exercise outcome) or non-responders (improvement less than the MID). Baseline physiological characteristics will then be compared between these groups. The primary aim of this study is to determine whether baseline physiological characteristics differ between people with ILD who respond to PR and those who do not.