Evaluating Physical Outcomes in Acute Respiratory Distress Syndrome Survivors: Validity, Responsiveness, and Minimal Important Difference of 4-Meter Gait Speed Test
Overview
Emergency Medicine
Authors
Affiliations
Objective: To examine the reliability, validity, responsiveness, and minimal important difference of the 4-m gait speed test in acute respiratory distress syndrome survivors.
Design: Secondary analyses of data from two longitudinal follow-up studies of acute respiratory distress syndrome survivors. Test-retest and inter-rater reliability, construct validity (convergent, discriminant, and known group), predictive validity, and responsiveness were examined. The minimal important difference was estimated using anchor- and distribution-based approaches.
Setting: A national multicenter prospective study (ARDSNet Long-Term Outcome Study) and a multisite prospective study in Baltimore, MD (Improving Care of Acute Lung Injury Patients).
Patients: Acute respiratory distress syndrome survivors with 4-m gait speed assessment up to 60 months after acute respiratory distress syndrome (ARDSNet Long-Term Outcome Study, n = 184; Improving Care of Acute Lung Injury Patients, n = 122).
Interventions: Not applicable.
Measurements And Main Results: Four-meter gait speed was assessed at 6- and 12-month follow-up (ARDSNet Long-Term Outcome Study) and 36-, 48-, and 60-month follow-up (Improving Care of Acute Lung Injury Patients). Excellent test-retest (intraclass correlation, 0.89-0.99 across studies and follow-up) and inter-rater (intraclass correlation, 0.97) reliability were found. Convergent validity was supported by moderate-to-strong correlations (69% of 32 > 0.40) with other physical function measures. Discriminant validity was supported by weak correlations (86% of 28 < 0.30) with mental health measures. Survivors with impaired versus nonimpaired measures of muscle strength and pulmonary function had significantly slower 4-m gait speed (all but one p < 0.05). Furthermore, 4-m gait speed significantly predicted future hospitalization and health-related quality of life. Gait speed changes were consistent with reported changes in function, supporting responsiveness. The estimated 4-m gait speed minimal important difference was 0.03-0.06 m/s.
Conclusions: The 4-m gait speed is a reliable, valid, and responsive measure of physical function in acute respiratory distress syndrome survivors. The estimated minimal important difference will facilitate sample size calculations for clinical studies evaluating the 4-m gait speed test in acute respiratory distress syndrome survivors.
Parrotte K, Mercado L, Lappen H, Iwashyna T, Hough C, Valley T CHEST Crit Care. 2025; 2(3.
PMID: 39822343 PMC: 11737505. DOI: 10.1016/j.chstcc.2024.100084.
Physical function measures in ICU survivors, where to now? A scoping review.
du Plessis I, Hanekom S, Lupton-Smith A South Afr J Crit Care. 2024; 40(2):e1742.
PMID: 39726835 PMC: 11669153. DOI: 10.7196/SAJCC.2024.v40i2.1742.
Davies T, Kelly E, van Gassel R, van de Poll M, Gunst J, Casaer M Crit Care. 2023; 27(1):450.
PMID: 37986015 PMC: 10662687. DOI: 10.1186/s13054-023-04729-7.
Mayer K, Kosmac K, Wen Y, Parry S, Dhar S, Foster S Front Physiol. 2023; 14:1231538.
PMID: 37936579 PMC: 10625915. DOI: 10.3389/fphys.2023.1231538.
Mayer K, Palakshappa J, Peltan I, Andrew J, Gundel S, Ringwood N Pilot Feasibility Stud. 2022; 8(1):212.
PMID: 36123599 PMC: 9483889. DOI: 10.1186/s40814-022-01151-8.