Reliability and reproducibility of six-minute walk test in healthy children

Abstract

Was verified the reproducibility of the six-minute walk test (6MWT) in Brazilian healthy children. A transversal cross-sectional observational study was carried out between October 2012 and July 2013, with healthy children aged between 6 and 14 years. Initially, the participants were assessed as biometric data (weight, height, body mass index, body surface area and length of the lower limbs) and spirometry. Two 6MWT were performed with 30min interval between them. The retest was carried out after two weeks. Statistical analysis included Shapiro-Wilk normality and analysis of variance (ANOVA) tests for comparison between the 6MWT; intraclass correlation coefficient - two way mixed model, consistency (ICC) were used to assess reproducibility, as well as the provision Bland & Altman. The level of significance was 5% (p<0,05). Were enrolled 29 children in the study (16 females, mean age 10,28±2,25 years). Reproducibility was found between the two longest 6MWT distances, with ICC=0,82 (p<0,001) as well as similarity in behavior of physiological parameters. The children walked similar distances in the first and second test on both days, showing a walking distance variation (Δ) both negative on day 1 and on day 2 (-5,52 m [confidence interval of 95% (95%CI) -28,475-17,417 m] and -2,26 m [95%CI -28,503-23,982 m], respectively). The 6MWT showed to be reproducible in healthy schoolchildren. The retest showed no improvement in the performance of the studied population, suggesting no learning effect.