Résumé :
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Background: The 6-minute walk test (6MWT) is a commonly used measure of cardiorespiratory endurance. Researchers have begun to use it as a strength related outcome measure in clinical trials in neuromuscular disease. We evaluated the 6MWT differentiation between boys with Duchenne muscular dystrophy (DMD) and healthy controls, tested variability in boys with DMD, and correlation of the 6MWT with timed functional measures. Methods: We enrolled ambulatory boys 12 years old with DMD (n=15) and without (n=20). Boys with DMD were tested 7 days apart using a modified American Thoracic Society 6MWT and standard clinical timed function testing. Healthy controls underwent testing at a single time point. Results: Across all ages, distance traveled differed between boys with DMD and healthy controls. In boys aged 5-6, those with DMD averaged 367 ± 74 m compared to 574 ± 35 m (p<.01) for the healthy controls. In boys aged 7-9, those with DMD averaged 354 +/- 31 m compared to 622 ± 50 m (p<.001) for the healthy controls. In boys aged 10-12, those with DMD averaged 265 ± 146 m compared to 646 ± 49 m (p<.001) for the healthy controls. As age increased in the DMD group, percent predicted scores decreased from 82% at age 5 to 56% at age 12. 6MWT test correlation was high (r=.92). In the DMD group, the 6MWT correlated well with time to walk 10 m (r=.80), time to walk 25 m (r=.80), time to climb 4 standard stairs (r=.77), and time to stand (r=.64). Conclusion: A modified 6MWT in ambulatory boys with DMD is reproducible, differentiates boys with DMD from healthy controls at all ages, and correlates with other measures of disease severity.
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