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+/-104 m and in the group without severe cardiac disease 280+/-104 m (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+/-88 m vs 317+/-85 m; 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.