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

https://doi.org/10.1016/j.apmr.2009.02.015Get rights and content

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.

Section snippets

Inclusion

Male and female adults with DS participated in this study. Recruitment took place in different locations: (1) patients that took part in a cardiac screening program for adults with DS. This cardiac screening program took place in The Prinsenstichting and in ASVZ, both institutions for people with intellectual disabilities, and was offered to all adults with DS living in these institutions Patients already treated by a cardiologist, patients with severe Alzheimer's disease, and patients that

Results

In total, 54 patients with DS living in the participating institutions performed the 6MWT. Ten patients were not able to perform the 6MWT because they sat in a wheelchair; 9 refused to perform the test. Twenty-seven DS patients with Eisenmenger syndrome from the outpatient clinics performed the 6MWT. Fourteen of them performed the 6MWT twice. In total, 81 adults with DS (mean age, 39±11y; 65% men) could be included in this study and were divided into 2 groups: 29 patients with severe cardiac

Discussion

In this study, we found that the 6MWD was not dependent on severity of cardiac disease in patients with DS. Therefore, the 6MWT is not a valid test to examine cardiac restriction in patients with DS. The level of intellectual disability was negatively correlated with the 6MWD and it was found to be an independent predictor of the 6MWD. The test-retest reliability of the 6MWT in patients with DS was adequate.

Conclusions

The findings of this study suggest that the 6MWT does not appear to be a valid indicator of cardiorespiratory fitness in adult patients with DS. The 6MWT appeared to be inversely related to intellectual disability in these patients. Future studies are needed to investigate other parameters that can be used to assess functional capacity in individuals with DS or modifications that can improve the validity of the 6MWT for this population.

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    A commercial party having a direct financial interest in the results of the research supporting this article has conferred or will confer a financial benefit on the author or one or more of the authors. Actelion Pharmaceuticals Nederland B.V. funded the honorarium of Dr. de Bruin-Bon.

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