Bisphosphonates Use and Risk of Subtrochanteric and Diaphyseal Femur Fractures in Korea: Results from the National Claim Registry

Although Asian with bisphosphonate has been considered to have higher risk of subtrochanteric and diaphyseal femur (ST/DF) fractures, the occurrence of those fractures has been still unclear in Asia. The purpose of this study was to investigate the incidence rate of ST/DF fractures among bisphosphonate users from nationwide database in South Korea. Using national health insurance claim database, we only included the bisphosphonate users who took bisphosphonate for the first time in 2008 and evaluated the incidence rate of ST/DF fracture from 2008 to 2013. Non-user controls were matched to bisphosphonate users by propensity score matching with age and gender. Cox regression models were used to calculate hazard ratios of ST/DF fracture with and without adjustment for comorbidity. A total of 682 ST/DF fractures were observed among 348,311 bisphosphonate users. The incidence rate of ST/DF fracture among bisphosphonate users (37.75/100,000 person years, 95% CI 35.02–40.70) was higher compared with non-users (24.41/100,000 person years, 95% CI 22.31–26.71). The risk of ST/DF fracture was greater in bisphosphonate users compared with non-users (hazard ratio 1.541, 1.370–1.734; p < 0.001). The incidence rate of ST/DF fracture after bisphosphonate use could be determined in Korean patients, which can provide basal information for further studies on risk and benefit of continuing bisphosphonate.