Objectives: Osteonecrosis of the jaw (ONJ) has been recently associated with exposure to bisphosphonates (BPs). Incidence and risk factors are ill-defined. This Dental PBRN study (www.dpbrn.org; support: DE-16746, DE-16747) used electronic records from two participating health plans to estimate ONJ incidence and relative risk vis-à-vis BP use.
Methods: We used multiple search strategies and manual chart reviews to identify ONJ cases within members of two large health plans. Our cohort was members age 35 and over, who had medical and pharmacy coverage for at least one year during 1994–2006. We used a keyword search of electronic physician notes to flag suspected cases among patients with a diagnosis, procedure, or medication indicative of ONJ. Cases were confirmed through manual chart review. Additional cases among cohort members were identified by oral surgeons and general dentists. We compared BP and other pharmacologic exposures, disease histories, and other characteristics of ONJ cases and non-cases within the cohort.
Results: Among a cohort of 572,858, our search and preliminary chart review for 37,290 members found 16 ONJ cases. Dental providers located nine more cases. Among cases, 37% had oral BPs and 16% had IV BPs, but 47% had no BP exposure. Overall, 19,104 cohort members received oral BPs for an average of 618 days. Among cases, 53% had a history of cancer and 32% had osteoporosis. Chart notes did not mention ONJ before mid-2005. Afterward, 79 patients discussed BPs and ONJ risks with their provider: 16% stopped BPs due to ONJ fear, and 8% received dentist or physician advice to stop taking BPs altogether or before planned dental care.
Conclusions: The incidence of ONJ in this cohort was very low. Most cases had cancer or osteoporosis, but nearly half had no BP exposure. Most ONJ discussions were driven by patient concerns about bisphosphonates.