Clinical use of the modified shuttle test in children with cystic fibrosis: Is one test sufficient?

Objective To evaluate the reproducibility of the modified shuttle test (MST) and to determine whether the test needs to be performed more than once to assess the exercise capacity of children and adolescents with cystic fibrosis (CF). Methods This was a longitudinal study including patients diagnosed with CF aged more than 6 years. The participants were followed for a period of 9 months and were evaluated at three different time points (visits 1, 2, and 3). Spirometric, anthropometric, clinical, and genetic data were collected, and two MSTs were performed at each visit. Results Forty‐eight clinically stable volunteers with a mean age of 10.1 ± 2.7 years were initially included. The reproducibility of the test was evaluated using the distance achieved (DA) as the main variable. There were no significant differences in the DA (visit 1, p = .23; visit 2, p = .24; visit 3, p = .85), baseline heart rate (HR) (visit 1, p = .35; visit 2, p = .20; visit 3, p = .98), and peak HR (visit 1, p = .16; visit 2, p = .94; visit 3, p = .23) between the tests performed at each visit. The test‐retest reliability demonstrated a high intraclass correlation coefficient at all visits (visit 1, 2, and 3: 0.83, 0.90, and 0.80, respectively) and the variation in HR was the main factor associated with the DA in the MST over time. Conclusion The MST was found to be a reproducible and reliable test. The data presented here support the use of a single MST to evaluate and monitor exercise capacity of patients with CF during clinic visits.