Treatment Persistence and Medication Switch Associated with Subsequent Fractures after Osteoporotic Fractures.

The study examined the association between persistence in anti-osteoporotic medication (AOM) and subsequent fractures, allowing for medication switching among patients with osteoporotic fractures. This retrospective cohort study used Taiwan National Health Insurance claims data. We selected patients who initiated AOM between 2013 and 2016. Treatment persistence was defined as whether the patients were on any AOM on a given day of interest with a 45-day grace period. Medication switch was allowed for persistence if remaining on treatment. AOM with long-lasting inhibition of bone resorption, such as zoledronate and denosumab, was categorized as high-potency AOM; otherwise, low-potency AOM. Multivariate Cox models were used to evaluate the risk of subsequent fractures 3 months or more after initiating AOM. A total of 119,473 patients were included, with a mean follow-up of 46.4 months (standard deviation, 15.6), and 26.8% switched from the index AOM. Within 1 year of follow-up, 52% remained persistent with AOM. Compared to patients with persistent AOM, those not persistent had a higher risk of subsequent hip (adjusted hazard ratio [aHR] = 1.31, 95% confidence interval [CI]:1.21-1.42), vertebral (aHR = 1.17, 95%CI:1.13-1.22), and radius fractures (aHR = 1.16, 95%CI:1.08-1.25). Patients with persistent AOM who switched from high- to low-potency AOM had a higher risk of subsequent vertebral fractures than those with persistent AOM and no potency switch (aHR = 1.28; 95%CI:1.02-1.60). Patients with non-persistent AOM had a higher risk of subsequent fractures than persistent users when allowing AOM switch. Switching AOM potency may influence the risk of subsequent vertebral fractures and warrants further investigation.