Pharmacoeconomic analysis of clopidogrel in secondary prevention of coronary artery disease

BACKGROUND: When used as an alternative to or in addition to aspirin, clopidogrel has been demonstrated by some but not all randomized controlled trials to be effective in secondary prevention of cardiovascular (CV) events in patients with (1) coronary artery disease (CAD), (2) acute coronary syndrome (ACS), and (3) coronary stent placement. However, a drawback to clopidogrel therapy is the cost to patients and the health care system. Clinical studies have also demonstrated that when clopidogrel is used in addition to aspirin, the combination has an increased bleeding risk compared with aspirin alone. Cost-effectiveness analysis may aid in developing strategies for optimal use of clopidogrel. OBJECTIVE: To review and evaluate published pharmacoeconomic analyses on the use of clopidogrel in secondary prevention of CV events in patients who have known CAD, have ACS, or are undergoing percutaneous coronary interventions (PCIs). METHODS: English-language peer-reviewed articles or abstracts were identified from MEDLINE and the Current Contents database (both from 1966 to August 15, 2006) using the search terms clopidogrel and pharmacoeconomics or clopidogrel and cost analyses. Citations from available articles were also reviewed for additional references. RESULTS: Multiple cost-effectiveness analyses of clopidogrel were available for review. These pharmacoeconomic studies were performed using different clinical databases from randomized controlled trials as well as observational databases. Cost was from the perspective of different health care systems and society; it was expressed in varying cost-effectiveness terms (life-year gained vs. per quality-adjusted life-year [QALY]). Although direct comparison among studies was difficult, clopidogrel appeared to be cost effective when used for up to 12 months in combination with aspirin (compared with aspirin alone) in patients with ACS or in those undergoing PCIs, using different societal perspectives (both in the United States [average U.S.$15,000 per QALY among U.S. studies reporting per QALY] and in European countries [United Kingdom reported 218,888 (average U.S.$28,300) per QALY]). In contrast, when used as an alternative to aspirin for secondary prevention of CAD, clopidogrel had mixed results in cost-effectiveness analyses (results varied from U.S.$25,000 to $114,000 per QALY). A major limitation of the models cited is the extrapolation of outcomes far beyond the duration used in the clinical trial database. CONCLUSION: On the basis of current cost-effectiveness data, clopidogrel should be used in addition to aspirin therapy for up to 12 months in all patients with non-ST elevation ACS as well as in those who received coronary stents. For secondary prevention of CAD, clopidogrel should be used only in those who cannot tolerate aspirin therapy.