The Impact of Exercise Tolerance Assessed by 6-Min Walking Distance on Clinical Outcomes in Patients With...

This study aimed to determine whether exercise tolerance assessed by 6-min walk distance (6MWD) predicts clinical outcomes in patients with connective tissue disease-associated interstitial lung disease (CTD-ILD).

This was an ambispective cohort study. We included patients in a stable condition with CTD-ILD. The 6MWD during hospitalization was used to determine the exercise tolerance. The primary endpoint was all-cause mortality, and the secondary endpoint was hospitalization for pulmonary disease. We examined the association between the 6MWD and each endpoint.

Among the 224 patients evaluated {median age 66.5 [interquartile range (IQR) 55.0-74.0] years; 146 females}, there were 23 deaths and 56 hospitalizations for pulmonary disease during the median follow-up period of 1.2 (IQR 0.6-2.3) years. The 6MWD of 310 m and 260 m were identified as optimal cut-off points for the prediction of all-cause mortality and hospitalization for pulmonary disease, respectively. The Kaplan-Meier survival curve showed that a higher 6MWD was associated with a lower rate of all-cause mortality and hospitalization for pulmonary disease (log-rank = 16.146, p < 0.001 and log-rank = 9.065, p = 0.003, respectively). After adjusting for clinical confounding factors, the hazard ratios for all-cause mortality and hospitalization for pulmonary disease per 10-m increase in 6MWD were 0.962 [95% confidence interval (CI): 0.927-0.998] and 0.968 (95% CI 0.946-0.991), respectively.

Higher exercise tolerance, as assessed by 6MWD, was independently associated with a better prognosis in stable patients with CTD-ILD.