Incidence and risk factors of bisphosphonate associated osteonecrosis of the jaws

Abstract

9074 Background: Intravenous bisphosphonate therapy has been used for treatment of various benign and malignant bone diseases, including bony metastasis. Recent single case reports have described osteonecrosis (ON) of the mandible or maxilla as a previously unknown complication of this therapy. Methods: Records of 638 patients treated with intravenous pamidronate or zoledronic acid were reviewed to determine the incidence of jaw ON. Number of infusions, dosing interval, dosage administered, and duration of treatment were analyzed to determine risk factors for the development of this complication. Results: Mean age of the study group was 67 years and 61% were female. The most common primary malignancies included prostate, lung, breast, and multiple myeloma. The overall incidence of osteonecrosis was 6/638 (0.94%). Patients treated with pamidronate (n=336), zoledronic acid (n=169), and both agents (n=133) had an incidence of ON of 1.2%, 0%, and 1.5% respectively (p=NS). No significant relationship was observed between the incidence of ON and demographic parameters, primary tumor, cumulative drug dose, or dosing interval. However, patients who developed ON had a significantly greater mean number of infusions (20.7 versus 10.7, p=0.016) and significantly greater mean hours of infusion time (42.7 versus 17.7, p=0.0036) than those who did not develop the complication. Underlying dental disease appears to be associated with ON. Conclusions: This review represents the largest single series to date of patients treated with IV bisphosphonate therapy. The findings suggest positive correlation between the development of ON and drug exposure as measured by number of infusions and total infusion hours. However, this data must be interpreted with caution as the overall incidence of the complication was low (<1%), precluding rigorous statistical analysis. Dental comorbidity should be addressed prior to initiation of bisphosphonate therapy. No significant financial relationships to disclose.