Medication persistence and risk of fracture among female Medicare beneficiaries diagnosed with osteoporosis.

We examined the relationship between persistent osteoporosis medication use and fracture risk among female Medicare beneficiaries diagnosed with osteoporosis using Medicare claims, 2009-2012. Persistent use was associated with reduced risk of fracture and significantly lower total health care costs in the follow-up period. Results were consistent using different analytical methods.
Introduction: This study aimed to examine the relationship between medication persistence and fracture risk among female Medicare beneficiaries diagnosed with osteoporosis.
Methods: Elderly female Medicare beneficiaries diagnosed with osteoporosis and initiated on osteoporosis medication January 1, 2009-June 30, 2011, were included. Persistent medication use was defined as continuous use (no gap ≥ 60 days) for 1 year or longer. The key outcome was fragility fracture. A difference-in-difference analysis was performed at the log scale of fracture rate using a Poisson regression model with months 1-6 before medication initiation as the pre-initiation period and up to 18 months after as the post-initiation period. Total health care costs were compared using a similar approach. Sensitivity analyses were conducted using different pre- and post-initiation periods.
Results: The study included 294,369 patients; 32.9% were persistent osteoporosis medication users and 67.1% non-persistent (< 12 months continuous use). Fracture incidence rates were 16.2 per 100 patient-years pre-initiation and 4.1 post-initiation for persistent users; corresponding rates for non-persistent users were 19.0 and 7.3 per 100 patient-years. The adjusted post-/pre-initiation fracture rate ratios were 0.284 for persistent and 0.411 for non-persistent users. The ratio of the two rate ratios was 0.692 (persistent vs. non-persistent, p < 0.0001), suggesting a significantly greater fracture rate reduction for persistent users. Adjusted cost ratios were significantly lower for persistent users. Sensitivity analyses results were similar.
Conclusions: Persistent use of osteoporosis medications was associated with reduced risk of fracture and significantly lower total health care costs. Payers and patients would benefit from interventions aimed at improving medication persistence.