The Risk of Osteonecrosis of the Jaws in Taiwanese Osteoporotic Patients Treated With Oral Alendronate or Raloxifene

Background: This study aimed to explore the possible association between osteonecrosis of the jaws (ONJ) and oral alendronate or raloxifene used for osteoporosis and to estimate its absolute and attributable risks in the Taiwanese population. Methods: Using an electronic medical records system and manual confirmation of ONJ, we identified patients who began taking alendronate or raloxifene for osteoporosis and developed ONJ between January 2000 and April 2012. Results: The incidence of ONJ associated with oral alendronate for the management of osteoporosis began after 1 year of drug exposure and progressively increased with longer durations of therapy, specifically from 0.23% to 0.92% as the duration of treatment went from 2 years to 10 years. The overall frequency of ONJ related to oral alendronate over a 12-year period was 0.55%. The incidence rate of ONJ attributed to alendronate exposure was 283 per 100 000 persons per year. On multivariate Cox proportional analysis, adjusting for the potential confounders, alendronate remains an independent predictor for ONJ occurrence [hazard ratio 7.42 (1.02-54.09)] compared with raloxifene. Advanced age, drug duration, and coexisting diabetes and rheumatoid arthritis are contributing factors to the development of oral alendronate-related ONJ. Conclusion: We provided the evidence to support the association of ONJ with oral alendronate used in the treatment or prevention of osteoporosis.