Minimal detectable change in six-minute walk test in children and adolescents with cystic fibrosis

Purpose: To provide test-retest reliability for the 6-min walk test and the physiological variables obtained during the test, and to establish the minimal detectable change for the distance walked in children and adolescents with cystic fibrosis. Methods: 40 patients performed two 6-min walk tests on the same day (separated by 30-min of rest). The perceived breathlessness and fatigue in the legs were assessed with the modified Borg scale. The peripheral muscle strength was assessed using a hand dynamometer device, the medicine ball throw test and the horizontal jump test. Results: The test-retest reliability of the distance walked, dyspnea and fatigue in the legs were good for children (minimal detectable change(90-95): 59.39-70.55 m) and for adolescents (minimal detectable change(90-95:) 47.81-56.8 m) with cystic fibrosis. Exercise tolerance is more related to 6-min walk work (distance walked x body weight) than to the distance walked alone and showed a positive association with peripheral muscle strength and forced vital capacity. Conclusions: The 6-min walk test is a reproducible and reliable tool to measure exercise tolerance for children and adolescents with cystic fibrosis. The minimal detectable changes reported for the distances achieved by these patients will be useful to identify the effectiveness of therapies aimed at alleviating or improving impaired physical capacity.

Automated summary

This study aimed to provide test-retest reliability for the 6-min walk test and physiological variables in children and adolescents with cystic fibrosis, and establish the minimal detectable change for the distances walked. Results showed good test-retest reliability for distance walked, dyspnea, and fatigue in the legs, with exercise tolerance being more related to 6-min walk work and positively associated with peripheral muscle strength and forced vital capacity.