Comparative effectiveness of generic and brand-name statins on patient outcomes: a cohort study.

Background: Statins are effective in preventing cardiovascular events, but patients do not fully adhere to them. Objective: To determine whether patients are more adherent to generic statins versus brand-name statins (lovastatin, pravastatin, or simvastatin) and whether greater adherence improves health outcomes. Design: Observational, propensity score-matched, new-user cohort study. Setting: Linked electronic data from medical and pharmacy claims. Participants: Medicare beneficiaries aged 65 years or older with prescription drug coverage between 2006 and 2008. Intervention: Initiation of a generic or brand-name statin. Measurements: Adherence to statin therapy (measured as the proportion of days covered [PDC] up to 1 year) and a composite outcome comprising hospitalization for an acute coronary syndrome or stroke and all-cause mortality. Hazard ratios (HRs) and absolute rate differences were estimated. Results: A total of 90 111 patients who initiated a statin during the study was identified; 83 731 (93%) initiated a generic drug, and 6380 (7%) initiated a brand-name drug. The mean age of patients was 75.6 years, and most (61%) were female. The average PDC was 77% for patients in the generic group and 71% for those in the brand-name group (P < 0.001). An 8% reduction in the rate of the clinical outcome was observed among patients in the generic group versus those in the brand-name group (HR, 0.92 [95% CI, 0.86 to 0.99]). The absolute difference was -1.53 events per 100 person-years (CI, -2.69 to -0.19 events per 100 person-years). Limitation: Results may not be generalizable to other populations with different incomes or drug benefit structures. Conclusion: Compared with those initiating brand-name statins, patients initiating generic statins were more likely to adhere and had a lower rate of a composite clinical outcome.