Skeletal effects and functional outcome with olpadronate in children with osteogenesis imperfecta a 2-year randomised placebo-controlled study

BACKGROUND: Non-randomised studies have suggested beneficial effects of bisphosphonates in osteogenesis imperfecta. We assessed the effects of oral olpadronate in children with this disorder in a randomised double-blind placebo-controlled trial.

METHODS: 34 children recruited from the Dutch national centre for osteogenesis imperfecta were randomly assigned olpadronate (10 mg/m2 daily; n=16) or placebo (n=18) for 2 years. All children also received calcium and vitamin D supplements. Primary endpoints were incident fractures of long bones and changes in bone mineral content (BMC), bone mineral density (BMD), and functional outcome. Anthropometry, vertebral height, and urinary markers of bone resorption were also studied. Analyses were by intention to treat.

FINDINGS: Fracture follow-up was complete for all the children, including two who withdrew from the study (one from each group). Olpadronate treatment was associated with a 31% reduction in relative risk of fracture of long bones (hazard ratio 0.69 [95% CI 0.52-0.91], p=0.01). The olpadronate group showed significantly greater increases than the placebo group in spinal BMC (difference between groups 2.24 g/year [0.20-4.29], p=0.03) and spinal BMD (difference between groups 0.054 g/cm2 per year [0.012-0.096], p=0.01). There were no detectable effects on functional outcome, anthropometrics, or vertebral height and no differences between the groups in changes in urinary markers of bone resorption.

INTERPRETATION: Oral treatment with olpadronate at a daily dose of 10 mg/m2 results in a reduction of fracture risk of long bones in children with osteogenesis imperfecta. However, the issue of whether bisphosphonates will alter the natural course of osteogenesis imperfecta remains unresolved, and further studies are needed.