Abstract
Fibrotic interstitial lung disease (F-ILD) is associated with substantial morbidity and mortality, in which exertional hypoxemia represents a key marker of disease severity. Although the six-minute walk test (6MWT) is the reference standard for its assessment, routine use is often limited by practical constraints. This study aimed to evaluate whether the three-minute walk test (3MWT) could serve as a pragmatic screening tool for detecting exertional hypoxemia.In this real-world cohort study, 82 patients with multidisciplinary discussion-confirmed F-ILD were enrolled. All patients underwent both 3MWT and 6MWT, along with pulmonary function testing. Correlations between oxygenation indices and the predictive performance of 3MWT parameters for identifying desaturation during the 6MWT (nadir SpO₂ 4.5% and nadir SpO₂ <90.5% during the 3MWT provided optimal discrimination (AUC 0.83). The 3MWT provides clinically relevant oxygenation information that correlates with standard 6MWT parameters and may serve as a practical screening and triage tool to identify patients at risk of exertional hypoxemia. It should be considered complementary to, rather than a replacement for, the 6MWT.