Reliability Validity and Minimal Detectable Change of Four-Step Stair ClimbPower Test in Community-Dwelling Older Adults

摘要

>Background. Stair climb power is an important clinical measure of lower-extremity power. The stair climb power test (SCPT) was validated by requiring individuals to climb a full flight of stairs. A 4-step SCPT (4SCPT) would be more clinically feasible and easier to perform, yet its reliability and validity are unknown. >Objective. To evaluate reliability, validity, and minimal detectable change of 4SCPT among community-dwelling older adults. >Design. This study is a cross-sectional analysis of baseline data from a clinical trial. >Methods. Fifty older adults ≥65 years of age, at risk for mobility decline, consented to participate in this ancillary study. Test-retest reliability was derived from 2 measurements within each participant measured by a single assessor. Pearson correlation analyses among leg power measures (4SCPT, SCPT, single leg press power at 40% and 70% of the 1-repetition maximum [SLP40, SLP70]) were performed. Separate multivariate linear regressions were conducted evaluating the associations between each leg power measure and 2 mobility outcomes, the Short Physical Performance Battery (SPPB) and habitual gait speed(HGS). Minimal detectable change was based on a 90% confidence interval(MDC90).>Results. The 4SCPT had excellent test-retest reliability (ICC(2,1) = 0.951),and strong correlation with SCPT, SLP40, and SLP70 (r = 0.85-0.96). The4SCPT explained a greater amount of variance in the SPPB (R² = 0.31) than otherleg power measurements (R² = 0.23-0.25). The 4SCPT (R² = 0.41) andSCPT (R² = 0.42) described equivalent amounts of variance in HGS, and greaterthan that with SLP40 (R² = 0.28) and SLP70 (R² = 0.30). TheMDC90 for 4SCPT was 44.0 watts.>Limitations. This was a cross-sectional analysis within a small,nonrepresentative sample. Interrater reliability was not evaluated.>Conclusions. The 4SCPT shows scientific promise as a valid and reliable legpower measurement among community-dwelling older adults.