A Cost-Effectiveness Analysis of Combination Antiplatelet Therapy for High-Risk Acute Coronary Syndromes: Clopidogrel plus Aspirin versus Aspirin Alone
- Mark D. Schleinitz, MD, MS; and
- Paul A. Heidenreich, MD, MS
- From Brown University and Rhode Island Hospital, Providence, Rhode Island; and Stanford University Medical Center and VA Palo Alto Healthcare System, Palo Alto, California.
Abstract
Background: Although clopidogrel plus aspirin is more effective than aspirin alone in preventing subsequent vascular events in patients with unstable angina, the cost-effectiveness of this combination has yet to be examined in this high-risk population.
Objective: To determine the cost-effectiveness of clopidogrel plus aspirin compared with aspirin alone.
Design: Cost–utility analysis.
Data Sources: Published literature.
Target Population: Patients with unstable angina and electrocardiographic changes or non–Q-wave myocardial infarction.
Time Horizon: Lifetime.
Perspective: Societal.
Interventions: Combination therapy with clopidogrel, 75 mg/d, plus aspirin, 325 mg/d, for 1 year, followed by aspirin monotherapy, was compared with lifelong aspirin therapy, 325 mg/d.
Outcome Measures: Lifetime costs, life expectancy in quality-adjusted life-years (QALYs), and the incremental cost-effectiveness ratio.
Results of Base-Case Analysis: Patients treated with aspirin alone lived 9.51 QALYs after their initial event and incurred expenses of $127 700; the addition of clopidogrel increased life expectancy to 9.61 QALYs and costs to $129 300. The incremental cost-effectiveness ratio for clopidogrel plus aspirin compared with aspirin alone was $15 400 per QALY.
Results of Sensitivity Analyses: The analysis of 1 year of therapy was robust to all sensitivity analyses. In the probabilistic sensitivity analysis, fewer than 3% of simulations resulted in cost-effectiveness ratios over $50 000 per QALY. The cost-effectiveness of longer combination therapy depends critically on the balance of thrombotic event rates, durable efficacy, and the increased bleeding rate in patients taking clopidogrel.
Limitations: This analysis may not apply to patients with severe heart failure, those undergoing long-term anticoagulant therapy, those recently managed with revascularization, or those undergoing short-term treatment with glycoprotein IIb/IIIa inhibitors.
Conclusions: In patients with high-risk acute coronary syndromes, 1 year of therapy with clopidogrel plus aspirin results in greater life expectancy than aspirin alone, at a cost within the traditional limits of cost-effectiveness. The durable efficacy of clopidogrel relative to the risk for hemorrhage should be further explored before more protracted therapy can be recommended.
Article and Author Information
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Grant Support: Dr. Schleinitz was supported in part by a Building Interdisciplinary Research Careers in Women's Health (BIRCWH) career development grant (HD43447) from the National Institutes of Health Office of Research on Women's Health, administered through Women and Infants' Hospital, Providence, Rhode Island. Dr. Heidenreich was supported by a Career Development Award from the Veterans Administration Health Services Research and Development Service (CD98326).
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Potential Financial Conflicts of Interest: None disclosed.
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Requests for Single Reprints: Mark D. Schleinitz, MD, MS, Division of General Internal Medicine, Brown University and Rhode Island Hospital, 593 Eddy Street, MPB-1, Providence, RI 02903; e-mail, Mark_Schleinitz{at}Brown.edu.
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Current Author Addresses: Dr. Schleinitz: Brown University and Rhode Island Hospital, Division of General Internal Medicine, 593 Eddy Street, MPB-1, Providence, RI 02903.
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Dr. Heidenreich: VA Palo Alto Healthcare System, 3801 Miranda Avenue, Palo Alto, CA 94304.
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Author Contributions: Conception and design: M.D. Schleinitz, P.A. Heidenreich.
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Analysis and interpretation of the data: M.D. Schleinitz, P.A. Heidenreich.
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Drafting of the article: M.D. Schleinitz.
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Critical revision of the article for important intellectual content: M.D. Schleinitz, P.A. Heidenreich.
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Final approval of the article: M.D. Schleinitz, P.A. Heidenreich.
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Statistical expertise: M.D. Schleinitz.
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Collection and assembly of data: M.D. Schleinitz.
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