Reliability and minimal detectable change of the Timed Up & Go test in COPD

Abstract

Background: Patients with COPD often exhibit balance impairments which impact on their daily life activities. Hence, health professionals should routinely monitor balance in this population. One simple and easy-to-employ clinical measure for this purpose is the Timed Up & Go (TUG) test. This measure has been increasingly used in COPD; however, its reliability and minimal detectable change (MDC) have not been established, limiting the interpretation of results. Aim: This study aimed to determine the inter- and intra-rater reliability and MDC for the TUG test in older patients with COPD. Methods: Patients (aged≥60 years) were invited to attend 2 sessions, with 48-72h interval. They performed the TUG test twice in each session. Tests were assessed by two raters in session 1 and one rater in session 2. Inter- and intra-rater reliability were calculated for the exact scores (using data from trial 1) and mean scores (mean of 2 trials) using Intraclass Correlation Coefficients (ICC 2,1 and ICC 2,2 , respectively). The MDC 95 was calculated from the standard error of measurement (SEM). Results: Sixty participants (72.43±6.90 years, FEV 1 65.03±22.60% predicted) completed session 1 and 41 participants session 2. Excellent ICC values were found for inter-rater (ICC 2,1 95%CI 0.995-0.998; ICC 2,2 95%CI 0.999-1) and intra-rater (ICC 2,1 95%CI 0.855-0.957; ICC 2,2 95%CI 0.931-0.981) reliability. The SEM was 0.97s and 0.66s and the MDC 95 was 2.68s and 1.84s considering the exact and mean scores, respectively. Conclusions: The TUG test is highly reliable in COPD and has an acceptable random measurement error. Findings may help health professionals to interpret when a change in patient9s performance corresponds to a true change.