Intravenous bisphosphonate therapy in children with osteogenesis imperfecta.

OBJECTIVE: Several studies have reported beneficial effects of bisphosphonates in children with osteogenesis imperfecta (OI); however, these studies have differed in the protocols they used, and none has been independently replicated. We intended to confirm the efficacy of a specific intravenous bisphosphonate protocol in children with moderate to severe OI.
METHODS: We used the protocol described by Glorieux et al and performed a prospective clinical trial in 6 children who were aged 22 months to 14 years. Each patient received intravenous pamidronate therapy for a minimum of 2 years in cycles of 1 mg/kg daily over 3 consecutive days at a mean cycle interval of 3.8 months. Outcome measures included lumbar spine areal bone mineral density (BMD) and z score, fracture rate, and occupational therapy functional assessment with serial Pediatric Evaluation of Disability Inventory.
RESULTS: While on therapy, the average annual increase in areal BMD was 48% and the average annual increase in BMD z score was 1.0. This increase in z score is statistically significant. There was no clear correlation between changes in BMD and fracture rate. All patients experienced functional improvement in mobility.
CONCLUSIONS: Our results support the findings of Glorieux et al that cyclic administration of intravenous pamidronate in children with OI has beneficial effects with respect to BMD z scores and physical disability. Long-term follow-up will be required to determine whether bisphosphonate therapy will decrease fracture rates and increase mobility in children with moderate to severe OI.