Test-retest reliability of the stair test in patients with total hip arthroplasty

Purpose Stair climbing is one of the important functional activities of daily living to maintain mobility and independence. Walking and stair climbing have been identified by clinicians and patients as critical functional activities before and after total hip arthroplasty (THA). Testing the ability to manage steps has been commonly used in clinical and research settings because it is an inexpensive and simple way to measure functional status after THA. The frequent use of this test supports studies seeking evidence to validate stair test (ST) as a measure of physical performance in subjects with THA. The aim of this study is to determine the test-retest reliability of the 9-step ST in patients with THA. Methods Patients performed twice trials for the ST on the same day with one hour interval. To assess test-retest reliability, the intra-class correlation coefficient – ICC (2,1), standard error of measurement (SEM), minimal detectable change at the 90% confidence level (MDC90) were calculated. Results A total of 37 patients with THA participated in this study. The ST showed very high reliability (ICC = 0.98 (95% CI, 0.96 to 0.99)). The SEM was 0.3 seconds and the MDC90 was 0.7 seconds. Conclusions Test-retest reliability of the ST was very high for the patients with THA, and the SEM and MDC90 were adequate for clinical use. The ST is less time consuming and has very high reliability to measure the functional level after THA in the clinical setting.