Predictors of statin compliance after switching from branded to generic agents among managed-care beneficiaries.

Abstract

To identify patient demographics and characteristics associated with compliance to statin therapy after switching from branded to generic agents Retrospective cohort study using electronic health records and pharmacy claims data from Sutter Health's ambulatory-care medical network Managed-care beneficiaries, ≥ 18 years of age, who were switched from branded to generic statins between 1 January 2003 and 31 December 2012 MAIN MEASURES: Compliance was calculated as days of therapy dispensed divided by days from first to last generic prescription fill over 6 months, and was defined as a medication possession ratio ≥ 0.80. We used multivariable logistic regression to assess factors associated with compliance. Adjusted ORs and 95% CI were generated. We identified 5,156 patients who were switched from branded to generic statins; 73% of patients were compliant in the 6 months after switching. After statistical adjustment, higher compliance was associated with each 10-year increase in age (OR: 1.13; 95% CI: 1.07, 1.19; p < 0.001), receipt of a generic statin equivalent in potency to the prior branded statin (OR: 1.41; 95% CI: 1.16, 1.70; p < 0.001), and compliance with prior branded statin (OR: 4.68; 95% CI: 4.07, 5.39; p < 0.001). Lower compliance was seen among Hispanic patients compared to non-Hispanic white patients (OR: 0.68; 95% CI: 0.52, 0.91; p = 0.009). Also, a switch to a higher potency generic statin, regardless of prior dose/potency, was negatively associated with compliance after switching (OR: 0.87; 95% CI: 0.80, 0.94; p = 0.001). The majority of patients switched from branded to generic agents were compliant with therapy in the first 6 months after switching. The potential for non-compliance to generic statin therapy, particularly among younger or Hispanic patients or when dose/potency changes are made, should be considered prior to switching. For these patients, counseling or close monitoring may be required to optimize generic interchange.