Efficacy of Zoledronic Acid on Bone Mineral Density in Boys With Duchenne Muscular Dystrophy: A Prospective Observational Study.

BACKGROUND

To evaluate the efficacy and safety of intravenous zoledronic acid (ZA) in improving bone mineral density (BMD) and reducing bone turnover in boys with Duchenne muscular dystrophy (DMD) from North India.

METHODS

In this prospective study, boys aged 5-18 years with genetically confirmed diagnosis of DMD, and either a history of low-impact long-bone or vertebral compression fractures (VCFs), or a lumbar spine/right femur neck dual-energy x-ray absorptiometry (DXA) BMD ≤ -2 z-score for age were enrolled. ZA was administered in three doses (total 0.125 mg/kg/year) at 3-month intervals. Outcomes assessed at 12 ± 2 months included changes in lumbar spine and femur neck BMD z-scores, VCFs number and grade, serum C-terminal telopeptide of type 1 collagen (CTX) levels, back pain, functional status, and quality of life.

RESULTS

Fifty-five boys (mean age 10.7 ± 2.4 years) were enrolled. Seven boys (13%) had 8 long-bone fractures, and 33 (60%) had 86 VCFs on spine radiographs. Lumbar spine BMD z-score improved by 0.67 (95% confidence interval: 0.42-0.91; P = 0.001), and femur neck z-score by 0.49 (95% confidence interval: 0.06-0.93; P < 0.001). VCFs prevalence remained unchanged, though 26.7% developed new grade 1 VCFs. Mean serum CTX levels decreased from 0.488 to 0.179 ng/mL post ZA therapy (P < 0.001). ZA was well tolerated with no serious adverse events. Functional status and quality-of-life scores remained stable.

CONCLUSIONS

Intravenous ZA significantly improved BMD and reduced bone turnover in boys with DMD without major adverse effects.