Reliability of gait performance tests in individuals with late effects of polio.

OBJECTIVE To assess the reliability of 4 gait performance tests in individuals with late effects of polio. DESIGN An intrarater (between occasions) test-retest reliability study. SETTINGS University hospital. PARTICIPANTS Thirty men and women (mean age 63 +/- 6.4 years) with clinically and electrophysiologically verified late effects of polio. INTERVENTION Not applicable. MAIN OUTCOME MEASURES The Timed "Up & Go" test, the Comfortable and the Fast Gait Speed tests, and the 6-Minute Walk test were assessed 7 days apart. Reliability was evaluated with the intraclass correlation coefficient (ICC(2,1)), the mean difference between the test sessions (d), and the 95% confidence intervals for d, the standard error of measurement (SEM and SEM%), the smallest real difference (SRD and SRD%) and the Bland & Altman graphs. RESULTS Test-retest agreements were high (ICC(2,1) 0.82-0.97) and measurement errors generally small. The standard error of measurement (SEM%), representing the smallest change that indicates a real (clinical) improvement for a group of individuals, was small (4%-7%). The smallest real difference (SRD%), representing the smallest change that indicates a real (clinical) improvement for a single individual also was small (12%-21%). CONCLUSION These commonly used gait performance tests are highly reliable and can be recommended to evaluate improvements in various aspects of gait performance in groups of individuals as well as single individuals with late effects of polio.