Distance travelled in the six-minute walk test in patients with chronic obstructive pulmonary disease as a predictor of mortality.

Background: Exercise intolerance in patients with COPD has significant implications for quality of life, hospitalization rates, and survival.

Objective: To assess functional capacity using the six-minute walk test (6MWT) by categorizing the distance walked in six minutes (6MWD) into tertiles and to assess the impact of this functional capacity on predictors of survival over a 24-month follow-up in patients with Chronic Obstructive Pulmonary Disease (COPD).

Methods: This prospective cohort study followed 118 patients with COPD for 24 months. Participants were stratified based on the 6MWD: Group 1 (mean distance 590-424 m); Group 2 (mean distance 423-337 m); and Group 3 (mean distance < 336 m). Symptoms and disease severity were assessed using CAT scores. Kaplan-Meier was used to determine the association between 6MWD and all-cause mortality.

Results: The 6MWD, stratified by functional performance, was a significant predictor of survival in patients with COPD, despite heterogeneity in disease severity between groups. The 6MWD, stratified by functional performance, was a significant predictor of survival in patients with COPD, despite heterogeneity in disease severity between groups. Furthermore, in regression analysis for mortality, it was identified for 6MWD (CI 0.994; p = 0.043) and peripheral oxygen saturation (SpO₂) (CI 0.735; p < 0.001). Kaplan-Meier survival analysis revealed that patients who walked less than 336 m in the 6MWD had the lowest probability of survival at 24 months (log-rank p < 0.05).

Conclusion: The 6MWD is a robust predictor of mortality over a 2-year period in patients with COPD, reflecting a broad spectrum of disease severity. Poorer 6MWD performance is associated with increased desaturation, impaired heart rate recovery, and greater symptom burden during exercise, as indicated by CAT scores.

Clinical trial number: Not applicable.