Fracture risk and impact in boys with Duchenne muscular dystrophy: A retrospective cohort study

Introduction/Aims Boys with Duchenne muscular dystrophy (DMD) are at increased risk of fracture. This study investigated the incidence of fractures, factors contributing to risk of first fracture with emphasis on body mass index (BMI), and the impact of fractures on functional capacity in an Australian cohort of boys with DMD. Methods A retrospective cohort study included boys with DMD who attended a pediatric neuromuscular clinic from 2011 to 2018. Information regarding fractures, anthropometry measurements, body composition and functional assessment was collected. Factors associated with first fracture risk were analyzed with Cox‐proportional hazards. Longitudinal analysis of function post‐fracture was also conducted. Results This study included 155 boys with DMD. At least one fracture occurred in 71 (45%) boys; overall incidence of fractures was 399‐per‐10,000 persons‐years. The first fracture was vertebral in 55%; 41% had non‐vertebral fractures and 4% had both. Vertebral fractures occurred in significantly older (12.28 vs 9.28 y) boys with longer exposure to glucocorticoids (5.45 vs 2.50 y) compared to non‐vertebral fractures. Boys with a history of fracture(s) had a steeper rate of functional decline (measured by Northstar Ambulatory Assessment score) than those with no recorded fractures. Discussion A high fracture burden was observed in a large Australian cohort of boys with DMD. Further investigation is required to understand preventative strategies and modifiable risk factors to reduce the incidence of fractures in DMD. The impact on fractures on ambulatory capacity should be closely monitored.