Prevalence and risk factors of bone fragility in duchenne muscular dystrophy: A systematic review and meta-analysis.

UNLABELLED: Duchenne muscular dystrophy (DMD) is an X-linked recessive disorder that is due to mutations in the dystrophin gene which encodes the dystrophin protein. Many patients face an increased risk of bone fragility and develop secondary osteoporosis as a result of the combined effects of progressive muscle weakness, immobilization, and the osteotoxic properties of glucocorticoids (GCs). The present study showed that the prevalence of low BMD and fracture in DMD patients reached as high as 0.62 and 0.38, respectively, with contributing risk factors extending beyond GCs and loss of ambulation to include older age, vitamin D deficiency, fat mass accumulation, and hormonal imbalances. Therefore, clinical trials of bone-protective therapies and strategies to improve bone health in boys with DMD are urgently warranted. PURPOSE: Poor skeletal health, characterized by rapid bone mineral density decline, causes substantial morbidity in patients with Duchenne muscular dystrophy (DMD). The present systematic review and meta-analysis aimed to review comprehensive findings on the prevalence and risk factors of low bone mineral density (BMD) and fractures in DMD. METHODS: PubMed, Embase, Cochrane library, and Web of Science databases were systematically searched for studies reporting prevalence of fractures, low BMD, or data on risk factors in DMD patients. Random‑effects meta‑analyses estimated pooled prevalence of low BMD and fractures. Subgroup analyses examined variations by region, GCs use, fracture location, and ambulatory stage. RESULTS: A total of 43 studies involving 4940 patients were reviewed. The prevalence of low BMD from 0.16 to 0.93, with an overall prevalence of 0.62 (95% CI, 0.45-0.79). Fracture prevalence spanned from 0.07 to 0.87, yielding a pooled estimate of 0.38 (95% CI, 0.32-0.43). North America had the highest fracture prevalence at 0.47 (95% CI, 0.39-0.56), followed by Oceania at 0.47 (95% CI, 0.40-0.54), Europe at 0.30 (95% CI, 0.24-0.37), and Asia at the lowest 0.17 (95% CI, 0.07-0.27). Fracture prevalence was higher in glucocorticoids (GCs)-treated patients (0.39 vs. 0.23 in non-GCs) and increased with longer GCs duration, being 0.23 (95% CI, 0.11-0.35) for 3 years, 0.33 (95% CI, 0.24-0.43) for 3-6 years, and 0.59 (95% CI, 0.42-0.75) for ≥ 6 years of GCs exposure. Bone fragility in DMD is driven by multifactorial risk factors, with contributors extending beyond GCs use and loss of ambulation to include older age, vitamin D deficiency, fat mass accumulation, and hormonal imbalances. CONCLUSION: Low BMD and fractures are highly prevalent globally in DMD, with bone fragility driven by multifactorial mechanisms. These findings may inform the design of clinical trials for bone-protective therapies and strategies to improve bone strength in this population.