The test-retest reliability and concurrent validity of the five times sit to stand test and step test in older adults with total hip arthroplasty.

Purpose: The aim of the study was to determine the test-retest reliability and concurrent validity of the five times sit to stand test (FTST) and step test (ST) in older adults with total hip arthroplasty (THA).
Methods: A cross-sectional and prospective study was carried out with 32 unilateral total hip arthroplasty patients. FTST, ST, and Timed Up & Go Test were evaluated at the first evaluation session. The test-retest reliability was evaluated by performing two repetitions of the FTST and ST. Besides, the functional status of the patients was evaluated with the Harris Hip Score (HHS). The test-retest reliability of the FTST and ST were assessed by the intraclass correlation coefficient (ICC). In the concurrent validity analysis, the Pearson correlation coefficient was analyzed. In addition, the standard error of measurement (SEM ₉₅ ) and minimal detectable change (MDC ₉₅ ) values of the FTST and ST were also calculated.
Results: The mean age of the participants was 75.4 ± 10.3 years. The ICC score of FTST, ST (right) and ST (left) were 0.987, 0.908 and 0.846, respectively. SEM ₉₅ and MDC ₉₅ values of the FTST were 1.05 and 2.91, respectively. FTST was correlated with both the HHS and TUG (r ₁  = -0.522, r ₂  = 0.730, p < 0.01). SEM ₉₅ and MDC ₉₅ values of the ST (right) were 0.37 and 1.02, respectively. SEM ₉₅ and MDC ₉₅ values of the ST (left) were 0.55 and 1.52, respectively. Also, ST (right) was only correlated with TUG (r = -0.654, p < 0.01). ST (right) were correlated with both the HHS and TUG (r ₁  = 0.503, r ₂  = -0.806, p < 0.01). The degree of correlations was strong.
Conclusion: The FTST and ST are valid and reliable performance tests in older adults with primary unilateral THA.
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