Comparison of the efficacy between once-monthly oral ibandronate and risedronate among Korean women with osteoporosis: a nationwide population-based study

Summary Using a nationwide database from the Korean National Health Insurance Service, this study showed that once-monthly oral ibandronate (150 mg) had better anti-fracture efficacy than once-monthly oral risedronate (150 mg), as seen on assessing overall and non-vertebral fractures among Korean elderly women with osteoporosis. Introduction Once-monthly oral bisphosphonates have been used widely without appropriate comparison. Therefore, we aimed to compare the anti-fracture efficacy of once-monthly ibandronate (150 mg) and once-monthly risedronate (150 mg). Methods We conducted a retrospective cohort study among Korean women aged ≥ 60 years from 2006 to 2015 using a nationwide database from the National Health Insurance Service Senior Cohort. The primary outcome was the first occurrence of fracture related to osteoporosis after the initial prescription of bisphosphonates. A Cox proportional model was used to estimate the incidence rate ratios (IRRs) and 95% confidence intervals (CIs) for overall and site-specific fractures between the two treatments, after adjusting for possible confounding factors. Results After propensity score matching, the ibandronate and risedronate groups, with 3454 patients each, were assembled from 36,701 new once-monthly ibandronate or risedronate users. After 4 years of follow-up, the ibandronate group had significantly lower incidence rates of overall and non-vertebral fractures than the risedronate group (IRR 0.822, 95% CI 0.698–0.968, P = 0.919 and IRR 0.798, 95% CI 0.647–0.985, P = 0.036, respectively). Conclusions Once-monthly ibandronate (150 mg) shows better anti-fracture efficacy than once-monthly risedronate (150 mg). However, further large-scale studies are required to confirm our findings and to determine site-specific differences, especially regarding the vertebral and hip areas.