Clinical Outcome of Patients with Osteogenesis Imperfecta on Intravenous Pamidronate Treatment at the Philippine General Hospital from 2010-2018

Abstract

Background. Osteogenesis imperfecta (OI) is a group of connective tissue disease characterized by propensity to fractures following minimal trauma. OI is a lifelong inheritable disease and currently has no definitive cure. Management goals are directed towards prevention of fractures, controlling the symptoms, maximizing independent mobility, and developing optimal bone mass and muscle strength. Bisphosphonates are the mainstay of pharmacologic fracture-prevention therapy for most forms of OI. The University of the Philippines-Philippine General Hospital Bisphosphonate Treatment Program for OI was started in 2006 by the Clinical Genetics Service. For more than a decade now, the program has been serving more than 50 OI patients. This study evaluated the clinical outcomes of the patients who were included in the program to add to the body of knowledge on Filipino patients with OI.

Objectives. This study sought to determine the clinical outcomes of children with OI on intravenous pamidronate treatment at the Philippine General Hospital (PGH) from January 2010 to December 2018.

Methods. The study utilized a retrospective review of medical records of 24 patients diagnosed with OI on pamidronate therapy seen at the PGH from January 2010 to December 2018. Descriptive statistics were used to summarize the demographic and baseline clinical characteristics of the patients. Median annualized fracture rates before and during treatment were calculated and compared. The patient functional mobility before and during pamidronate infusion was classified accordingly based on the Gross Motor Function Classification System (GMFCS) and were compared.

Results. Twenty-four patients, which include seven males and 17 females, with ages at the time of conduct of the study ranging from four years to 11 years, fulfilled the inclusion criteria. There were four patients with OI type I, six with OI type III, 11 with OI type IV and three with OI type V. The annualized long bone fracture rate decreased significantly from a median of 2.0/year (range 1-2.75) to 0.75/year (range 0-1) after more than a year on pamidronate infusion (p<0.001). There is a note of overall improvement in terms of functional mobility using the 5-point scale of the GMFCS during pamidronate infusion from the baseline. However, the difference is not statistically significant.

Conclusion. Cyclic intravenous pamidronate treatment in young children with moderate-severe OI is well tolerated and associated with reduced fracture frequency with a tendency to improvement of gross functional mobility.