source: Neuromuscular Disorders
N. Miller, L. Alfano, K. Flanigan, S. Al-Zaidy, C. Tsao, J. Mendell, L. Lowes
The 100-meter timed test (100m) has been proposed as an outcome measure for use in Duchenne muscular dystrophy (DMD) that has the potential to expand the recruitment pool to include both younger and more able boys as it is a concrete concept of running 2 laps around a set of cones. Many of the current assessments used in DMD have a ceiling effect as the most able boys can achieve a perfect score. The 100m eliminates the ceiling effect by allowing the boys to run if able. Although the most able boys may walk as fast as age matched peers, their running speeds are significantly slower. This study documents the sensitivity of the 100m to measure decline in boys with DMD over time. To this end, 40 boys with DMD (age range: 4–13 years) performed the 100m at baseline and then repeated testing at subsequent regularly scheduled clinic visits with time points at 6 months (N = 30), 12 months (N = 17), 18 months (N = 10), and 24 months (N = 2). Longitudinal change in time to complete the 100m was consistent with natural history studies in other functional measures as it improved until the age of 7 and then declined over time. Spearman’s rho showed excellent correlations between the 100m and other functional tests performed at concurrent visits including the Six Minute Walk Test (n = 51; r=-0.744, p < 0.001), North Star Ambulatory Assessment (n = 88; r=-0.877, p < 0.001), Time to Rise (n = 82; r = 0.768, p < 0.001), and Ten Meter Walk/Run Test (n = 97; r = 0.926, p < 0.001). Change in percent predicted 100m time over a 6 month (mean = -2.9 ± 7.8) and 12 month (mean = -6.0 ± 9.5) time period suggest it would be an optimal outcome measure in upcoming clinical trials. Sample size calculations using the change in 6 months and 12 months will be presented to demonstrate the utility of the 100m for future clinical trial planning as it could expand the recruitment pool and shorten trial duration.
Nationwide Children’s Hospital, USA