introduction: Glucocorticoid (GC) therapy in Duchenne muscular dystrophy (DMD) has altered disease progression, necessitating contemporary natural history studies.
Methods: The Cooperative Neuromuscular Research Group (CINRG) DMD Natural History Study (DMD-NHS) enrolled 340 DMD males, ages 2-28 years. A comprehensive battery of measures was obtained.
Results: A novel composite functional "milestone" scale scale showed clinically meaningful mobility and upper limb abilities were significantly preserved in GC-treated adolescents/young adults. Manual muscle test (MMT)-based calculations of global strength showed that those patients <10 years of age treated with steroids declined by 0.4 ± 0.39 MMT unit/year, compared with -0.4 ± 0.39 MMT unit/year in historical steroid-naive subjects. Pulmonary function tests (PFTs) were relatively preserved in steroid-treated adolescents. The linearity and magnitude of decline in measures were affected by maturational changes and functional status.
Conclusions: In DMD, long-term use of GCs showed reduced strength loss and preserved functional capabilities and PFTs compared with previous natural history studies performed prior to the widespread use of GC therapy.
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