Drug holiday patterns and bisphosphonate-related osteonecrosis of the jaw

Objectives: There is limited evidence regarding the appropriate length of a bisphosphonate (BP) holiday to reduce the risk of osteonecrosis of the jaw (ONJ). In this cross-sectional study, we investigated the population-based patterns of the gaps between BP discontinuation and ONJ diagnosis. Subjects and Methods: We used the claims database of the National Health Insurance Service in Korea. Among BP users between 2006 and 2015, incident ONJ cases during 2010–2015 with no history of ONJ in the last 4 years were identified. We assessed the time gap from the last BP administration to ONJ diagnosis. Results: Among 1,569 incident ONJ cases, 836 (53.3%) occurred after BP discontinuation. The cumulative proportions of ONJ occurrence within 1 month, 3 months, 1 year, 2 years, and 3 years after discontinuation were 58.9%, 70.8%, 87.0%, 93.2%, and 96.1%, respectively. The length of drug holidays showed no significant difference between patients with or without comorbid cancer and diabetes mellitus (p-value, 0.12 and 0.52, respectively). However, the use of injectable BP formulations significantly affected ONJ incidence (p < 0.01). Conclusions: Most ONJ cases occurred within 3 years from BP suspension, with a higher prevalence among BP injection users with 1 year or lesser BP holiday.