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

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. Arch Phys Med Rehabil 2009;90:1423-7. 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