Association Between Functional Tests and Mortality in Patients with Interstitial Lung Disease

<bold>Introduction:</bold> Individuals with interstitial lung disease (ILD) are often assessed using functional tests due to limited access to more complex exercise tests. However, the association between these functional tests and mortality in ILD is not well-studied. <bold>Aims:</bold> TO explore the relationship between functional tests and 5-year mortality in ILD patients. <bold>Methods:</bold> This is a longitudinal study where participants with ILD underwent pulmonary function assessment (spirometry, plethysmography, and carbon monoxide diffusing capacity [DLCO]) and six functional test protocols: 4-metre gait speed (4MGS), three sit-to-stand (STS) protocols (5 repetitions [5-STS], 30 seconds [30-STS], and 1 minute [1-STS]), and timed-up-and-go (TUG) at usual (TUGu) and maximum (TUGmax) speeds. Participants were followed for 5 years, and Cox regression models were used to evaluate the risk of mortality over this period. <bold>Results:</bold> The study included 50 participants with ILD (20 men [40%]; age 59±11 years; forced vital capacity 52±14 % predicted; DLCO 51±21 % predicted). A total of 13 participants (26%) died within 5 years. Among the Cox regression models conducted with functional tests, only 5-STS showed a significant association: 4MGS, HR: 1.02 [0.39-2.63], P=0.97; 5-STS, HR: 1.37 [1.07-1.77], P=0.01; 30-STS, HR: 0.91 [0.76-1.09], P=0.30; 1-STS, HR: 0.92[0.81-1.05], P=0.21; TUGu: 1.30 [0.89-1.90], P=0.17; TUGmax, HR: 0.88 [0.56-1.40], P=0.60). Even after adjusting for age, 5-STS maintained a significant association with mortality (HR: 1.30 [1.02 – 1.66], P=0.03). <bold>Conclusion:</bold> 5-STS is as a significant prognostic factor for 5-year mortality in ILD patients, with a 30% higher risk per additional second in the test.