Test-retest reliability, minimal detectable change and minimal clinically important differences in modified shuttle walk test in children and adolescents with cystic fibrosis

Abstract

Background: In youths with cystic fibrosis (CF) the modified shuttle walk test (MSWT) has been shown to be useful for assessing exercise tolerance; however, no studies to date have evaluated the reliability of MSWT, the minimal detectable change (MDC) and the minimal clinically important differences (MCID) for the MSWT distance for children and adolescents with CF.

Methods: Test-retest reliability: 35 CF patients and 34 healthy controls performed two MSWTs (separated by 2-4 days). MCID: 33 patients were invited to participate in a 6-week home-based exercise program consisting of 30-60-min sessions, 5 days a week.

Results: The test-retest reliability of the MSWT distance for children and adolescents with CF was excellent, obtaining a MDC₉₀ and MDC₉₅ of 97.08 m and 115.32 m, respectively. The test-retest reliability also was excellent in healthy controls, founding a MDC₉₀ and MDC₉₅ of 69.12 m and 82.11 m, respectively. The ROC curve analysis established (with a sensitivity of 82% and specificity of 76%) that a change of 60 m represented MCID.

Conclusions: The MSWT is a reliable tool to measure of exercise tolerance in children/adolescents with CF and those without CF. We propose a change in the score of at least 97.08 m (MDC₉₀) as the most appropriate value for assessing the exercise response of children and adolescents with CF, given that this value exceeds the MCID based on the children's perception.

Keywords: Children and adolescents; Cystic fibrosis; Physical activity; Pulmonary rehabilitation; Shuttle walk test; Submaximal exercise testing.