Factors associated with clopidogrel use, adherence, and persistence in patients with acute coronary syndromes undergoing percutaneous coronary intervention

Objective: Recent guidelines recommend use of aspirin and either clopidogrel or prasugrel for at least 12 months following use of drug-eluting or bare metal stents in patients with acute coronary syndromes (ACS) undergoing percutaneous coronary intervention (PCI). This study evaluated factors associated with clopidogrel use and adherence in ACS patients following PCI. Research design and methods: The US employer-based MarketScan commercial claims database was used to examine factors associated with clopidogrel use and adherence. Adherence was defined as a medication possession ratio of 80% higher. Multivariate logistic regression analyses were conducted to identify factors associated with clopidogrel use and adherence and included patient demographics, comorbidities, and prior beta-blocker, statin, and angiotensin converting enzyme inhibitor (BSI) use as factors. Results: A total of 10,465 patients aged 18-65 years who met inclusion criteria were hospitalized for ACS and underwent PCI between 01/01/2005 and 12/31/2006. Overall, the rate of clopidogrel use was 92.8% for ACS-PCI patients and 66.8% of the clopidogrel users were adherent. Receiving PCI without stenting (Odds Ratio [OR] = 3.28), comorbid hypertension (OR = 1.50), diabetes (OR = 1.49), and atrial fibrillation (OR = 1.91) were associated with decreased filled prescriptions for clopidogrel. Younger age (OR = 0.83) and prior use of clopidogrel (OR = 0.54) or other BSI medications (OR = 0.44) were associated with increased use of clopidogrel (all p values < 0.05). Factors significantly associated with non-adherence of clopidogrel were prior use of clopidogrel (OR = 1.40), prior hospitalization (OR = 1.34), chronic pulmonary disease (OR = 1.31), PCI without stenting (OR = 1.32), diabetes (OR = 1.17), and younger age (OR = 1.29). Prior use of BSI medications (OR = 0.82) increased adherence to clopidogrel. Conclusions: Prior use of clopidogrel, comorbid conditions such as diabetes and chronic pulmonary disease, prior hospitalization, PCI without stenting, and younger age had a negative impact on clopidogrel adherence. These findings may assist programs to improve thienopyridine compliance through a better understanding of patients' disease profiles and concomitant medication use.