Introduction: Exercise testing is useful in the respiratory evaluation of patients with cystic fibrosis. The shuttle walk test (SWT) is a progressive, externally paced, exercise test requiring the subject to walk/run back and forth between two fixed points. The aim is to assess the reproductibility of the SWT in paediatric patients with cystic fibrosis.
Methods: This prospective study recruited 31 children with stable disease. The patients performed two SWT one day (SWT 1 and 2) and two others (SWT 3 and 4) within 15 days. Only SWT 2 and 4 were assessed for reproducibility.
Results: 61% were boys, median age (range): 12.9 (7-18.9) years, median Shwachman score (range): 80 (65-100), median values for FEV1 and FVC (range): 92 (55-154) and 92 (64-140)% predicted, respectively. Median distance for SWT 2-4 (range): 910 (580-1020) and 925 (540-1020) metres. Reproducibility for SWT distance and physical activity measured by an accelerometer is very good (intra-class correlation coefficient=0.90 and 0.92, respectively). SWT distance correlated with physical activity (p=3.10(-4)) and weight (p=0.03). SWT distance was independent of the following parameters: height, weight-for-age Z-score, FEV1, FVC, Shwachman score, colonisation with Pseudomonas aeruginosa.
Conclusions: The SWT is reproducible in paediatric patients with cystic fibrosis and provides assessment of respiratory performance that complements spirometric measures of lung function.