Does tablet formulation alone improve adherence and persistence: a comparison of ezetimibe fixed dose combination versus ezetimibe separate pill combination?

Abstract

Aims: The aim of this study was to compare adherence and persistence in patients who add ezetimibe to statin therapy as a separate pill combination (SPC) or fixed dose combination (FDC). Method: This is a retrospective cohort study of prescription data conducted in an Australian health dataset. Two cohorts were identified: those dispensed statins and subsequently ezetimibe as either SPC or FDC. We compared adherence to combination therapy using the medication possession ratio (MPR), multivariate linear and logistic regression. Persistence to initial combination medicines and any lipid-lowering therapies were analysed using Kaplan Meyer survival and Cox proportional hazards models. Results: A total of 3651 people initiated ezetimibe SPC and 5740 ezetimibe FDC. There was no significant difference in adherence with mean MPRs: ezetimibe SPC = 0.99 (95% confidence interval 0.98–1.01) and FDC = 0.97 (95% CI 0.95–0.99). One year persistence rates to initial combination medicines were ezetimibe SPC 49.1% vs. FDC 62.4%; hazard ratio (HR) = 1.81 (95% CI 1.76–1.90). However, persistence to any lipid-lowering therapy was higher in those initiating ezetimibe SPC = 84.9% vs. FDC = 76%; HR = 0.62 (95% CI 0.55–0.72). One year persistence rates to any two lipid-lowering medicines were similar: ezetimibe SPC 65.2% and FDC 65%. Conclusion: In this study FDCs have little impact on either adherence or persistence to combination lipid-lowering therapy in people who have been taking statins. The benefit of higher persistence to FDCs in first episode of treatment with initial medicines is debatable as persistence to dual therapy was similar in both cohorts.