Muscle function and age are associated with loss of bone mineral density in Duchenne muscular dystrophy

Introduction: Patients with Duchenne muscular dystrophy (DMD) demonstrate decreased bone mineral density (BD). It is not clear which factors exert the greatest impact on BD loss in these patients. Methods: In 63 patients with DMD, serum cytokines (interleukin [IL]-1, IL-6, and tumor necrosis factor-beta [TNF-beta]), C-reactive protein (CRP), creatine kinase (CK), muscle function (by Vignos scale), body composition, and total BD (the latter 2 measured by dual-energy X-ray absorptiometry, or DEXA) were determined. Results: The main factors associated with BD loss were muscle function (34.0%; beta = -0.139; P < 0.023) and age (36.7%; beta = -0.151; P = 0.004). Cytokines, CRP, body fat mass, and CK did not contribute to BD loss. Discussion: Muscle function and age contribute to BD loss in DMD. We propose that a cut-off of at least 6 points for the Vignos scale and at least 10.5 years of age predict a Z-score of less than or equal to -2.0. Muscle Nerve 59:417-421, 2019