Low persistence with oral biphosphonate treatment in postmenopausal osteoporosis

Background: Osteoporotic fractures are a major cause of morbidity and mortality. It is recognized that persistence with medication is crucial to reach optimal clinical outcomes. We aimed to estimate the persistence level to weekly and monthly oral bisphosphonates (OBP) in women with postmenopausal osteoporosis (PMO) over 24 months from therapy initiation in a population-based setting. Methods: Prospective observational cohort study of PMO women ≥50 years initiating OBP recruited through community pharmacies. Data were collected at baseline during face-to-face interviews. Follow-up included pharmacy records (refill dates and medication possession; cohort 1) and telephone-surveys for patients who agreed to be interviewed (cohort 2). Patients were classified as persistent if they refilled their prescription within 30 days after exhausting the time covered by their previous supply. Log-rank tests were used to compare Kaplan-Meier curves of time to non-persistence. Results: Of 427 women recruited with a mean age of 65.0 years, 380 (89%) agreed to be interviewed (cohort 2). Over 24-months of follow-up, 3.4% (95% CI: [2.0%; 5.6%]) of all subjects were persistent to OBP based on pharmacy records. Analysis combining both self-reported information and pharmacy records (cohort 2) showed a persistence estimate of 20.0% (95% CI: [16.1%; 24.2%]). Lower persistence was associated with more frequent OBP dosing and living alone. The most common reason for treatment discontinuation was self-reported adverse events (27.6%). Conclusions: Results indicate a low level of persistence with OBP. Barriers and reasons leading to discontinuation of anti-PMO therapies should be proactively addressed to promote persistence and improve fracture protection.