A claims database analysis of persistence with alendronate therapy and fracture risk in post-menopausal women with osteoporosis

Objective: To explore the relationship between persistence with alendronate therapy and fracture rates in women with postmenopausal osteoporosis. Research design and methods: Claims data from a large US health plan database were used to examine persistence with therapy in postmenopausal women followed for 24 months. Persistence was defined as the time (in days) from the date of first fill to the run-out date of the last prescription with no lapses > 30 days after completion of the previous refill. A persistent cohort (length of persistence >= 182 days) and a nonpersistent cohort (length of persistence < 182 days) were defined. The number of patients with a fracture claim in each cohort was determined. Cox-proportional hazards regression (HR) analysis was used to determine significant differences in fracture rates between the two cohorts. Results: 4769 patients were followed for 24 months. Patients in the persistent cohort were significantly more likely to receive a treatment (vs. prevention) dose of alendronate (p = 0.03) and to be older than 65 years (p = 0.04). There was a trend toward more fractures in the non-persistent (4.9%) than in the persistent cohort (3.9%; p = 0.09). When controlled for other significant factors (including age and previous fractures) patients in the persistent cohort were 26% less likely to have a fracture diagnosis claim during the study period than those in the non-persistent cohort (HR = 0.74; 95% Cl, 0.549-0.996; p = 0.045). Prescription fill data are an indirect measure of medication-taking behavior. The use of claims data to estimate persistence and identify fracture events prohibits the establishment of causality between these two variables. Conclusion: Study results demonstrated that non-persistence with therapy, along with previous fracture and increasing age, was associated with a greater risk of fracture.