Assessment of the determinants of changes and test–retest reliability in the 6-min walk test performance over a 4-month period in healthy 6–12-year-old children

Abstract

Purpose: The purpose of the study is to establish the determinants of change in 6-min walk test (6MWT) performance observed in children aged 6–12 years over a 4-month period, and to provide test–retest reliability (4 months) to establish the minimal detectable change (MDC). Methods: Healthy children aged 6–12 years performed two 6MWT trials separated by a period of 4 months. Multiple linear regression analysis was performed to estimate the percentage of variance explained by the variables potentially predictive of the change in the 6MWT. We employed the intraclass correlation coefficient to assess test–retest reliability. Results: Fifty-nine children (28 boys and 31 girls) were assessed. The change in distance covered during the 6MWT was significantly correlated with the growth in their height (r = 0.679; p < 0.05) and the change in their weight (r = 0.473; p < 0.05). Multiple linear regression analysis shows that the change in distance covered in the 6MWT was only explained by its growth in height (46.0% explained variance). The test–retest reliability was fair-good. After 4 months, we established a 12% change from the initial measurement (79.69 m) as the MDC for a 90% confidence level (MDC90). Conclusions: The distance covered in the 6MWT improved as the children’s age, weight and height increased. The growth children's height was the most important predictor of change in distance covered in the 6MWT. An increase of at least 79.69 m (MDC90) in distance covered in the 6MWT is necessary to attribute the improvement to an intervention and not to the individual's growth.