Treatment Persistence and Medication Switch Associated With Subsequent Fractures After Osteoporotic Fractures.

Context: Despite prevalent anti-osteoporosis medication (AOM) switching in real-world osteoporosis management, few studies have evaluated the impact of persistent AOM treatment, allowing for AOM switching, on the risk of subsequent fracture.

Objective: We examined the association between persistence in AOM and subsequent fractures, allowing for medication switching among patients with osteoporotic fractures.

Methods: This retrospective cohort study used Taiwan National Health Insurance claims data to select patients who initiated AOM between 2013 and 2016. Treatment persistence was defined as use of any AOM on a given day of interest with a 45-day grace period. Medication switch was allowed for persistence if remaining on treatment. AOMs with long-lasting inhibition of bone resorption (zoledronate and denosumab) were categorized as high-potency; others as low-potency. Multivariate Cox models were used to evaluate risk of subsequent fractures ≥3 months after initiating AOM.

Results: A total of 119 473 patients were included (mean [SD] follow-up 46.4 [15.6] months), and 26.8% switched from the index AOM. Within 1 year, 52% remained persistent with AOM. Compared to patients with persistent AOM, those not persistent had higher risk of subsequent hip (adjusted hazard ratio [aHR] = 1.31; 95% 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 higher risk of subsequent vertebral fractures than those with persistent AOM and no potency switch (aHR = 1.28; 95% CI, 1.02-1.60).

Conclusion: Patients with non-persistent AOM had 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.