The reliability and validity of the L-test in people with Parkinson's disease

Objective To evaluate the test-retest and concurrent validity of the L-test in a group of participants with mild to moderate Parkinson's disease. The L-test is an extended version of the Timed up and Go test, incorporating a longer walking distance and turns in two directions. Design Cross-sectional. Setting Community. Participants 16 participants (13 male), mean age 75 (SD 6.7) mean duration since diagnosis 7.1 years (+/- 2.8). Disease severity was mild to moderate on the Hoehn and Yahr scale (mean 2.1; mode 2; range 1-3). 14 participants (12 male) completed the study. Interventions Not applicable. Main outcome measures A Bland and Altman plot examined the agreement between first and second testing occasion of the L-test. Intra-class correlation coefficients (ICC) assessed the test-retest reliability. Concurrent validity was established by correlating the L-test with the Timed up and Go test (TUG). The Minimal Detectable Change with 95% confidence interval (MDC95) was calculated to determine the true change not due to chance. Results The L-test showed excellent test-retest reliability on the Bland & Altman plot and the ICC. There was a high degree of agreement between measurements taken on days 1 and 2. The L-test correlated strongly with the Timed up and Go test on both measurement days with r = 0.97 (p < 0.001) and r = 0.96 (p < 0.001). The MDC95 was 5.31 seconds. Conclusions The L-test is a reliable and valid outcome measurement for the assessment of walking ability in participants with mild to moderate Parkinson's disease. (C) 2017 Chartered Society of Physiotherapy. Published by Elsevier Ltd. All rights reserved.