Field Walking Tests Are Reliable and Responsive to Exercise Training in People With Non–Cystic Fibrosis Bronchiectasis

Abstract

© 2015 Wolters Kluwer Health, Inc. All rights reserved. PURPOSE:: The 6-Minute Walk Test (6MWT) and Incremental Shuttle Walk Test (ISWT) are used to assess exercise capacity, but the reliability and responsiveness of these tests in individuals with non–cystic fibrosis (CF) bronchiectasis have not been determined. This study aimed to determine the reliability and responsiveness of both tests in adults with non-CF bronchiectasis. METHODS:: Eighty-five participants completed 2 6MWTs and 2 ISWTs in random order. Testing was repeated at the conclusion of an 8-week intervention period of exercise training. Reliability was assessed using intraclass correlation coefficients (ICC) and Bland-Altman analysis. Responsiveness was measured by effect size (ES) and standardized response mean (SRM). RESULTS:: At baseline, test-retest reliability was high for both tests (ICC = 0.95). The mean (95% CI) increase in the 6MWT from test 1 to test 2 was 20 m (13-26 m): 3% (0-5%) change. The mean (95% CI) increase in the ISWT was 15 m (4-25m): 4% (2-6%) change. A significant learning effect persisted after 8 weeks for the 6MWT (P = .04), but not the ISWT (P = .61). The 6MWT ES was 0.32 and SRM was 0.68; for the ISWT, ES was 0.42 with SRM of 0.71. CONCLUSION:: The 6MWT and ISWT are reliable measures of exercise capacity in non-CF bronchiectasis and responsive to exercise training. The small learning effect in both measures at baseline suggests that 2 of each test are necessary to correctly assess exercise capacity. Completion of 2 6MWTs at followup may minimize the risk of underestimating a treatment effect. CONDENSED ABSTRACT:: The reliability and responsiveness of the 6-Minute Walk Test (6MWT) and Incremental Shuttle Walk Test (ISWT) in non–cystic fibrosis bronchiectasis are unknown. Eight-five participants undertook the 6MWT and ISWT at baseline and following an intervention. Both tests were reliable (with a small learning effect) and responsive to exercise training.