Six-Minute Walk Test in Patients With Down Syndrome: Validity and Reproducibility

Abstract

Vis JC, Thoonsen H, Duffels MG, de Bruin-Bon RA, Huisman SA, van Dijk AP, Hoendermis ES, Berger RM, Bouma BJ, Mulder BJ. Six-minute walk test in patients with Down syndrome: validity and reproducibility. Objectives To examine the validity of the six-minute walk test (6MWT) as a tool to evaluate functional exercise performance in patients with Down syndrome (DS). Design Comparison of the six-minute walk distance (6MWD) in 2 distinct groups of DS patients: with and without severe cardiac disease. To test reproducibility, a group of patients with DS performed the 6MWT twice. Setting Tertiary referral centers for patients with congenital heart defects and outpatient clinics for people with intellectual disabilities. Participants Adult patients with DS with (n=29) and without (n=52) severe cardiac disease categorized by cardiac echocardiography. Interventions Not applicable. Main Outcome Measure Distance walked on the 6MWT. Results The mean 6MWD in the group with severe cardiac disease was 289±104m and in the group without severe cardiac disease 280±104m ( P=.70). Older age, female sex, and severe level of intellectual disability were all found to be independently and significantly correlated with a lower 6MWD ( r=.67, P<.001). The paired 6MWD was not significantly different (310±88m vs 317±85m; P=.40) in patients who performed the 6MWT twice. The coefficient of variation was 11%. Conclusions The 6MWD between the 2 groups was not significantly different. However, the walking distance inversely correlated with the level of intellectual disability. Therefore, the 6MWT is not a valid test to examine cardiac restriction in adult patients with DS.