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Randomized Controlled Trial
. 2013 Sep;48(3):357-68.
doi: 10.1002/mus.23905. Epub 2013 Jul 17.

The 6-minute walk test and other clinical endpoints in duchenne muscular dystrophy: reliability, concurrent validity, and minimal clinically important differences from a multicenter study

Craig M McDonald  1 , Erik K Henricson, R Ted Abresch, Julaine Florence, Michelle Eagle, Eduard Gappmaier, Allan M Glanzman; PTC124-GD-007-DMD Study Group; Robert Spiegel, Jay Barth, Gary Elfring, Allen Reha, Stuart W Peltz
Collaborators, Affiliations
Free PMC article
Randomized Controlled Trial

The 6-minute walk test and other clinical endpoints in duchenne muscular dystrophy: reliability, concurrent validity, and minimal clinically important differences from a multicenter study

Craig M McDonald et al. Muscle Nerve. 2013 Sep.
Free PMC article

Abstract

Introduction: An international clinical trial enrolled 174 ambulatory males ≥5 years old with nonsense mutation Duchenne muscular dystrophy (nmDMD). Pretreatment data provide insight into reliability, concurrent validity, and minimal clinically important differences (MCIDs) of the 6-minute walk test (6MWT) and other endpoints.

Methods: Screening and baseline evaluations included the 6-minute walk distance (6MWD), timed function tests (TFTs), quantitative strength by myometry, the PedsQL, heart rate-determined energy expenditure index, and other exploratory endpoints.

Results: The 6MWT proved feasible and reliable in a multicenter context. Concurrent validity with other endpoints was excellent. The MCID for 6MWD was 28.5 and 31.7 meters based on 2 statistical distribution methods.

Conclusions: The ratio of MCID to baseline mean is lower for 6MWD than for other endpoints. The 6MWD is an optimal primary endpoint for Duchenne muscular dystrophy (DMD) clinical trials that are focused therapeutically on preservation of ambulation and slowing of disease progression.

Keywords: 6-minute walk test; Duchenne muscular dystrophy; PedsQL; ambulation; energy expenditure index; muscular dystrophy; myometry; natural history; timed function test.

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Figures

FIGURE 1
FIGURE 1
Reliability of the 6-minute walk distance (6MWD) test–retest.
FIGURE 2
FIGURE 2
Correlation of velocity during 10-m walk/run vs. 6 minute walk distance (6MWD) at baseline. Note that a mean value of 358 m on 6MWD corresponds to a velocity of 1.64 m/s = 6 s on 10-m run/walk.
FIGURE 3
FIGURE 3
(a) Left frame: Correlation of knee extension strength (pounds) with percent predicted 6-minute walk distance (6MWD) at baseline. (b) Right frame: Correlation of knee extension strength per kilogram body weight with percent predicted 6MWD at baseline using age- and height-calculated formula.,
FIGURE 4
FIGURE 4
Relationship between energy expenditure index (EEI expressed in units of beats per meter) and percent predicted 6MWD in 174 DMD subjects at baseline.
FIGURE 5
FIGURE 5
Correlation between 6MWD and PedsQL Physical Function Scale (n = 174 DMD evaluated at baseline).
See this image and copyright information in PMC

Comment in

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