Objectives: The aim of this study was to determine the effect of dose frequency on compliance and persistence with bisphosphonate therapy in postmenopausal women and to compare findings from 3 different health care systems.
Methods: Three independently performed retrospective cohort analyses were performed using observational data sources. In the United States, bisphosphonate-naive postmenopausal women were identified from a database providing information on health plan prescription drug claims; in the United Kingdom and France, bisphosphonate-naive postmenopausal women were identified from a database of medical records supplied by general practice physicians. The women were grouped into 2 cohorts: those who were initiated on a weekly regimen of alendronate 70 mg or risedronate 35 mg and those initiated on a daily regimen of alendronate 5 or 10 mg or risedronate 5 mg. Compliance was measured in terms of the medication possession ratio (MPR), which was defined as the proportion of days in the 12-month follow-up period for which patients were covered by prescriptions for bisphosphonates. Persistence was measured as the number of days from the date of the index prescription to the last day of prescription coverage within the followup period. Women were classified as nonpersistent if the gap between prescriptions was > 30 days.
Results: The study included 2741 postmenopausal women with osteoporosis from the United States, 7567 from the United Kingdom, and 5332 from France. The mean (SD) age of the women was 73.0, 71.7, and 69.7 years in the 3 countries, respectively. The overall MPR was 61% in the United States, 74% in the United Kingdom, and 58% in France. In all 3 countries, women on a weekly regimen had a significantly greater MPR than women on a daily regimen (69% vs 58%, respectively, in the United States; 76% vs 64% in the United Kingdom; and 59% vs 53% in France; all, P < 0.001). Women on a weekly regimen of bisphosphonates persisted with treatment significantly longer than women on a daily regimen (227 vs 185 days, respectively, in the United States; 249 vs 208 in the United Kingdom; and 179 vs 155 in France; all, P < 0.001). A significantly greater proportion of the women on a weekly regimen persisted with treatment for 12 months compared with those on a daily regimen (44% vs 32%, respectively, in the United States; 52% vs 40% in the United Kingdom; and 51% vs 44% in France; all, P < 0.001).
Conclusions: In all 3 countries, postmenopausal women prescribed a weekly regimen of bisphosphonates had significantly greater rates of compliance than women prescribed a daily regimen, and they persisted longer with treatment. However, compliance and persistence rates were suboptimal for both regimens.