The Validity, Reliability, Measurement Error, and Minimum Detectable Change of the 30‐Second Fast‐Paced Walk Test in Persons with Knee Osteoarthritis: A Novel Test of Short‐Distance Walking Ability

Abstract

Objective To develop and establish the reliability, validity, measurement error, and minimum detectable change of a novel 30‐second fast‐paced walk test (30SFW) in persons with knee osteoarthritis (OA) that is easy to administer and can quantify walking performance in persons of all abilities. Methods Twenty females with symptomatic knee OA (mean age [SD] 58.30 [8.05] years) and 20 age‐ and sex‐matched asymptomatic controls (57.25 [8.71] years) participated in the study. Participants completed questionnaires of demographic and clinical data, the Knee Injury and Osteoarthritis Outcome Score (KOOS), and the 36‐item Short Form Health Survey (SF‐36) followed by 30SFW performance. Participants returned 2‐7 days later and performed the 30SFW again. Results The knee OA group reported function that was worse than controls (all KOOS subscales; P \u3c 0.0001). The 30SFW intrarater and interrater reliability were excellent [ICC(2,1) = 0.95‐0.99]. Knee OA participants walked a shorter distance in the 30SFW than controls (mean [SD]: OA 44.4 m [9.5 m]; control 58.1 m [7.8 m]; P \u3c 0.0001). Positive strong correlations were found between the 30SFW and the KOOS–Activity of Daily Living, SF‐36‐Physical Functioning, and SF‐36‐Physical Health Composite scores (P \u3c 0.0001). A nonsignificant, weak correlation between 30SFW and SF‐36‐Mental Health scores was present (r = 0.32, P = 0.05). Conclusion The 30SFW has excellent intrarater and interrater reliability. The 30SFW demonstrated excellent known groups, convergent, and discriminant validity as a measure of short‐distance walking ability in persons with knee OA. Clinicians and researchers should consider using the 30SFW to quantify walking ability in persons with knee OA and assess walking ability change