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

OBJECTIVES: To identify patient demographics and characteristics associated with compliance to statin therapy after switching from branded to generic agents DESIGN: Retrospective cohort study using electronic health records and pharmacy claims data from Sutter Health's ambulatory-care medical network PATIENTS: 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. KEY RESULTS: 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). CONCLUSIONS: 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.