Visualizing ambulatory performance by age and rates of decline among patients with Duchenne muscular dystrophy

In Duchenne muscular dystrophy (DMD), age at symptom onset and rate of decline thereafter vary considerably. This study contrasted disease progression over time using the North Star Ambulatory Assessment (NSAA) in an overall sample of patients with DMD (mean age 7.1 years; baseline total NSAA score 22.2) with that of a centrally representative subgroup (mean age 6.9 years; NSAA score 24.0) defined according to median age at loss of ambulation. The average disease trajectory in the overall sample understated the more rapid rates of decline experienced by patients in the centrally representative subgroup.