4 phenotypic characteristics tied to slow gait speed in idiopathic pulmonary fibrosis
Using the 4-metre gait speed (4MGS), a simple, reliable, valid and responsive tool, may help detect a patient with worse exercise performance, dyspnoea, health status and prognosis index in stable idiopathic fibrosis (IPF), suggests a study.
Intraclass correlation coefficients were 0.996 for interobserver and 0.983 for test–retest reliability. A robust association was observed between 4MGS and 6-min walking distance (6MWD; r, 0.76; p<0.0001), while moderate correlations existed with Medical Respiratory Council (MRC) dyspnoea score (r, –0.56), King’s Brief Interstitial Lung Disease (KBILD; r, 0.44) questionnaire, and Gender, Age and lung Physiology (GAP) prognostic index (r, –0.41; p<0.005 for all).
Pulmonary rehabilitation significantly improved 4MGS (mean change, 0.16 m/s; 95 percent CI, 0.12–0.20 m/s; effect size, 0.65). Despite similar lung function and high resolution computed tomography (HRCT) parameters, patients with slow vs preserved 4MGS had significantly worse exercise performance (6MWD, –167 m; –220 to –133 m), dyspnoea, health status and prognosis index.
The authors determined 4MGS interobserver (n=46) and test–retest (n=46) reliability, concurrent validity (n=65 and n=62) and responsiveness (n=60) in four prospective IPF cohorts. They also compared the phenotypic characteristics of all patients stratified according to slow 4MGS (<0.8 m/s), including lung function parameters, HRCT of the chest, 6MWD, MRC dyspnoea score, KBILD questionnaire and GAP prognostic index.
“Usual 4MGS is an established functional performance measure in older adults that consistently predicts adverse health outcomes, but few data exist in IPF,” the authors said.