Retrospective Cohort Study of Osteonecrosis of the Jaws

In the past two years, the literature has described more than 200 cases of osteonecrosis of the jaws (ONJ) among patients treated with bisphosphonates (BPs). About 3 million patients have been treated with BPs and another 7-8 million osteoporotic or cancer-afflicted persons in the U.S. may take BPs in the near future. To date, the prevalence of ONJ has not been quantified, nor is it known whether exposure to BPs actually increases ONJ prevalence. We investigated these issues using data from a large cohort of patients from the Kaiser Permanente Northwest and HealthPartners medical and dental plans. Both health maintenance organizations are part of DPBRN, allowing us to take advantage of an already-functioning interdisciplinary collaborative infrastructure.

This study addressed three specific aims. Aim 1 quantified the annual, consecutive prevalence of confirmed ONJ cases in a large cohort of adults 40 years of age and older from 1994 to 2005. Aim 2 tested the hypothesis that BP treatment is a risk factor for ONJ. We quantified the impact of BP exposure on the risk of developing ONJ, relative to comparable patients not exposed to BP, using a retrospective cohort design and time-to-event analysis. Finally, Aim 3 tested the hypothesis that ONJ develops only in patients treated with BPs who have additional risk factors. These health maintenance organizations provided a unique, unprecedented opportunity to investigate ONJ by including thousands of patients through their electronic medical and dental records.

Relevance to public health: In light of the substantial morbidity due to ONJ, this study provided important information about this growing health concern.