The test-retest reliability and concurrent validity of performance-based task tests in patients with knee osteoarthritis.

BACKGROUND:The measurement tool used for an accurate balance assessment should produce valid and reliable results in the population in which it is used. OBJECTIVES:To examine whether two performance-based task tests are a reliable and valid measurement test to assess balance in patients with early and advanced knee osteoarthritis (KO). DESIGN:Reliability and concurrent validity research. METHOD:Test-retest reliability by calculating the intraclass correlation coefficient (ICC) between the first and second trial periods of performance-based task tests (Alternate Step Test & Pen Pick up Test); their correlations with the Timed Up and Go Test (TUGT) were calculated and their concurrent validity in balance assessment were examined. RESULTS:A total of 100 patients (75% women, 25% men, mean 59 ± 10 years) with KO, 50 early (54 ± 7 years, 34 women, 16 men) and 50 advanced (64 ± 9 years, 41 women, 9 men), participated in the study. The ICC values for the Alternate Step Test (AST) and Pen Pick up Test (PPT) in patients with early KO are 0.881 (0.747-0.939, 95% confidence intervals) and 0.815 (0.689-0.892, 95% confidence intervals), respectively, while it is 0.852 (0.752-0.913, 95% confidence intervals) and 0.861 (0.756-0.922, 95% confidence intervals) in patients with advanced KO. Pearson correlation coefficient between AST & PPT times and TUGT time in patients with early and advanced KO was in the range of 0.535-0.746 (p < 0.01). CONCLUSIONS:Both task tests are reliable and valid clinical measurement tests that can be used to assess balance in patients with both early and advanced KO.