INVESTIGATING THE RELIABILITY AND VALIDITY OF A HOME-BASED PROTOCOL TO ASSESS PHYSICAL FUNCTION

Abstract

PURPOSE: To investigate the reliability and validity of a home-based (HB) physical function testing kit. METHODS: In this 2-arm, test-retest study, 21 participants (ages 20-84) performed 2 HB testing sessions within 24 hours (test-retest) and a single lab-based (LB) testing session. Testing order was assigned randomly. Tests of physical function included hand grip strength (HGS), chair stands completed in 30 seconds (CS-30s), time to 5 stands (CS-TT5), 4-meter gait speed (4MW), and 6-minute walk (6MW). Reliability was assessed by intraclass correlation coefficient (ICC) between the HB test-retest. Validity was assessed with Bland-Altman plots and estimated limits of agreement (LoA) between the HB and LB tests. RESULTS: Right HGS, left HGS, and 6MW displayed excellent reliability (ICC = .93, .95 and .97, respectively). CS-30 and CS-TT5 displayed good reliability (ICC = .88 and .86, respectively). 4MW displayed moderate reliability (ICC = .68). LoA were -6.1 – 3.2kg and -6.2 – 3.7kg for right and left HGS, respectively; -4.4 – 4.6 repetitions for CS-30; -3.24 – 2.55s for CS-TT5; -.31 – .40m/s for 4MW; and -81.4 – 81.2m for 6MW. Only HGS assessments displayed acceptable validity based on MCIDs. CONCLUSION: This HB testing kit presents an option to increase accessibility and utility of PF testing, and while test-retest reliability is promising, modifications are necessary to improve the validity of this testing protocol.