Prognostic value of gait speed for exacerbations and mortality in COPD

Gait speed, a key component of exercise capacity, has been underutilised in COPD, despite its prognostic potential. We aimed to evaluate the association between gait speed and clinical outcomes in COPD using 3-year longitudinal data from the Korean COPD Subgroup Study cohort.

Poor gait speed (<1.0 m·s^-1) was defined by usual pace during the 6-min walk test per Asian Working Group for Sarcopenia 2019 criteria. Lung function, symptoms, acute exacerbations (AEs) and mortality were compared between gait speed groups. Analyses included propensity score-matching, quartile classification, subgroup analyses and longitudinal trajectory modelling using random coefficient models.

Among 2063 participants, poor gait speed (n=831, 40.3%) was associated with older age, higher symptom burden and more previous AEs despite similar lung function. This group showed higher AE risk and frequency than the normal-speed group: adjusted odds ratios 1.37-1.45 for moderate and 1.64-1.65 for severe AEs; adjusted incidence rate ratios 1.24-1.36 for moderate and 1.63-1.86 for severe AEs. The 3-year mortality was significantly higher in the poor-gait-speed group (adjusted hazard ratio 2.30, 95% CI 1.42-3.73). Longitudinally, the poor-gait-speed group demonstrated persistently worse COPD Assessment Test (CAT) and St George's Respiratory Questionnaire for COPD scores at baseline, with modest CAT worsening over time (+0.44 point/year, p=0.01), while lung function decline was similar.

Gait speed provides a simple, integrative marker that independently predicts exacerbation risk, mortality and symptom progression in COPD.