Change in gait speed and adverse outcomes in patients with idiopathic pulmonary fibrosis: A prospective cohort study

Abstract

AbstractBackground and ObjectiveGait speed is associated with survival in individuals with idiopathic pulmonary fibrosis (IPF). The extent to which four‐metre gait speed (4MGS) decline predicts adverse outcome in IPF remains unclear. We aimed to examine longitudinal 4MGS change and identify a cut‐point associated with adverse outcome.MethodsIn a prospective cohort study, we recruited 132 individuals newly diagnosed with IPF and measured 4MGS change over 6 months. Death/first hospitalization at 6 months were composite outcome events. Complete data (paired 4MGS plus index event) were available in 85 participants; missing 4MGS data were addressed using multiple imputation. Receiver‐Operating Curve plots identified a 4MGS change cut‐point. Cox proportional‐hazard regression assessed the relationship between 4MGS change and time to event.Results4MGS declined over 6 months (mean [95% CI] change: −0.05 [−0.09 to −0.01] m/s; p = 0.02). A decline of 0.07 m/s or more in 4MGS over 6 months had better discrimination for the index event than change in 6‐minute walk distance, forced vital capacity, Composite Physiologic Index or Gender Age Physiology index. Kaplan–Meier curves demonstrated a significant difference in time to event between 4MGS groups (substantial decline: >−0.07 m/s versus minor decline/improvers: ≤−0.07 m/s; p = 0.007). Those with substantial decline had an increased risk of hospitalization/death (adjusted hazard ratio [95% CI] 4.61 [1.23–15.83]). Similar results were observed in multiple imputation analysis.ConclusionIn newly diagnosed IPF, a substantial 4MGS decline over 6 months is associated with shorter time to hospitalization/death at 6 months. 4MGS change has potential as a surrogate endpoint for interventions aimed at modifying hospitalization/death.