To measure the adherence and persistence of patients with acute coronary syndrome (ACS) initiating prasugrel after percutaneous coronary intervention (PCI).Methods
Using the Thomson Reuters MarketScan Commercial and Medicare Supplemental database, a retrospective cohort study identified patients initiating prasugrel following ACS-PCI hospitalization in 2009-2011. Prasugrel adherence over 12 months was measured using the medication possession ratio (MPR); predictors of adherence were identified using a logistic regression model. Persistence was defined as time on continuous therapy; a Cox model identified predictors of prasugrel discontinuation.Results
Among 1,340 patients, the mean age was 57 years; 79.5 % were male. Median prasugrel MPR was 93.2 %; 69.0 % of patients had an MPR ≥80 %. Predictors of adherence <80 % included prior PCI [odds ratio (OR) 0.60; 95 % confidence interval (CI) 0.40-0.90], prior depression (OR 0.37; 95 % CI 0.16-0.84), prior bleeding (OR 0.41; 95 % CI 0.19-0.86), and baseline anticoagulant use (OR 0.13; 95 % CI 0.03-0.55). Baseline statin use predicted higher adherence (OR 1.56; 95 % CI 1.21-2.02). The median duration of prasugrel therapy was 259 days. Predictors of discontinuation included prior anemia [hazard ratio (HR) 1.63; 95 % CI 1.21-2.21], prior cardiomyopathy (HR 2.72; 95 % CI 1.44-5.13), and prior ischemic heart disease (HR 1.15; 95 % CI 1.00-1.32); baseline statin use predicted reduced risk of discontinuation (HR 0.85; 95 % CI 0.75-0.97).Conclusions
Although adherence to prasugrel was generally high, the duration of therapy was frequently below recommendations. An awareness of risk factors for low adherence or early discontinuation can point to appropriate targets for intervention.