Gait speed and prognosis in patients with idiopathic pulmonary fibrosis: a prospective cohort study

Abstract

The four metre gait speed (4 MGS), a simple physical performance measure and surrogate marker of frailty, consistently predicts adverse prognosis in older adults. We hypothesised that 4 MGS could predict all-cause mortality and non-elective hospitalisation in patients with idiopathic pulmonary fibrosis (IPF).4 MGS and lung function were measured at baseline in 130 outpatients newly diagnosed with IPF. Survival status and non-elective hospital admissions were recorded over one year. We assessed the predictive value of 4 MGS (as a continuous variable and as a binary variable: slow versus preserved 4 MGS) by calculating hazard ratios (HR) using Cox proportional regression, adjusting for potential confounding variables. Receiver Operating Characteristic curves assessed discrimination between the multivariable regression models and established prognostic indices.Continuous 4 MGS and slow 4 MGS were independent predictors of all-cause mortality (4 MGS: HR 0.03 (0.01-0.31), p=0.004; slow 4 MGS: 2.63 (1.01-6.87), p=0.049) and hospitalisation (4 MGS: HR 0.02 (0.01-0.14), p<0.001; slow 4 MGS: 2.76 (1.16-6.58), p=0.02). Multivariable models incorporating 4 MGS or slow 4 MGS had better discrimination for predicting mortality than either the Gender Age Physiology index or Composite Physiologic Index.In patients with IPF, 4 MGS is an independent predictor of all-cause mortality and non-elective hospitalisation.