Early termination of six-min walk test in COPD as simple prognostic marker vs. BODE index

Abstract

Background: The 6-min walk test (6MWT) is commonly used to assess functional capacity in chronic obstructive pulmonary disease (COPD). While total distance walked is the main metric, early termination-stopping before 6 min-may reflect systemic vulnerability. This study evaluated whether early termination predicts poor outcomes and compared its prognostic value with the BODE index. Methods: Data were derived from a Korean COPD multicenter prospective cohort involving 55 hospitals. A total of 2085 patients were included in the present analysis. Early termination was defined as stopping the 6MWT before 6 min due to symptoms or clinical decision. Primary outcomes were acute exacerbations (AEs) of COPD; secondary outcomes included 3-year mortality and longitudinal changes in forced expiratory volume in 1 s (FEV1), COPD Assessment Test (CAT), and St. George's Respiratory Questionnaire for COPD (SGRQ-C) scores. Analyses included regression models, receiver operating characteristic curve, and propensity score matching. Results: Early termination occurred in 132 patients (6.3 %). They had lower post-BD FEV1 (48.4 % vs. 59.2 %) and higher symptom burden (CAT and SGRQ-C, all P < 0.01). Early termination was associated with increased risk of moderate (adjusted incidence rate ratio [aIRR] 1.60-1.65) and severe AEs (aIRR 2.19-2.39), and higher 3-year mortality (9.5 % vs. 4.6 %, log-rank P = 0.04). Its prognostic performance was comparable to the BODE index (DeLong P > 0.05). Conclusion: Early termination during the 6MWT is a simple, practical marker of poor outcomes in COPD, offering prognostic value comparable to the BODE index and aiding risk stratification when full assessment is impractical.