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Aspirin for the Primary Prevention of Cardiovascular Events: A Summary of the Evidence for the U.S. Preventive Services Task Force
- Michael Hayden, MD, MPH;
- Michael Pignone, MD, MPH;
- Christopher Phillips, MD, MPH; and
- Cynthia Mulrow, MD, MSc
- From University of North Carolina at Chapel Hill, Chapel Hill, North Carolina; and Air Force Medical Operations Agency and University of Texas Health Science Center at San Antonio, San Antonio, Texas.
Abstract
Background: The use of aspirin to prevent cardiovascular disease events in patients without a history of cardiovascular disease is controversial.
Purpose: To examine the benefits and harms of aspirin chemoprevention.
Data Sources: MEDLINE (1966 to May 2001).
Study Selection: 1] Randomized trials at least 1 year in duration that examined aspirin chemoprevention in patients without previously known cardiovascular disease and 2) systematic reviews, recent trials, and observational studies that examined rates of hemorrhagic strokes and gastrointestinal bleeding secondary to aspirin use.
Data Extraction: One reviewer read and extracted data from each included article and constructed evidence tables. A second reviewer checked the accuracy of the data extraction. Discrepancies were resolved by consensus.
Data Synthesis: Meta-analysis was performed, and the quantitative results of the review were then used to model the consequences of treating patients with different levels of baseline risk for coronary heart disease. Five trials examined the effect of aspirin on cardiovascular events in patients with no previous cardiovascular disease. For patients similar to those enrolled in the trials, aspirin reduces the risk for the combined end point of nonfatal myocardial infarction and fatal coronary heart disease (summary odds ratio, 0.72 [95% CI, 0.60 to 0.87]). Aspirin increased the risk for hemorrhagic strokes (summary odds ratio, 1.4 [CI, 0.9 to 2.0]) and major gastrointestinal bleeding (summary odds ratio, 1.7 [CI, 1.4 to 2.1]). All-cause mortality (summary odds ratio, 0.93 [CI, 0.84 to 1.02]) was not significantly affected.
For 1000 patients with a 5% risk for coronary heart disease events over 5 years, aspirin would prevent 6 to 20 myocardial infarctions but would cause 0 to 2 hemorrhagic strokes and 2 to 4 major gastrointestinal bleeding events. For patients with a risk of 1% over 5 years, aspirin would prevent 1 to 4 myocardial infarctions but would cause 0 to 2 hemorrhagic strokes and 2 to 4 major gastrointestinal bleeding events.
Conclusions: The net benefit of aspirin increases with increasing cardiovascular risk. In the decision to use aspirin chemoprevention, the patient's cardiovascular risk and relative utility for the different clinical outcomes prevented or caused by aspirin use must be considered.
Article and Author Information
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Disclaimers: The authors of this article are responsible for its contents, including any clinical or treatment recommendations. No statement in this article should be construed as an official position of the Agency for Healthcare Research and Quality, the U.S. Department of Defense, or the U.S. Department of Health and Human Services.
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Acknowledgments: The authors thank Kathleen Lohr, PhD; Sonya Sutton, BSPH; and Sheila White of Research Triangle Institute and Carol Krasnov of the University of North Carolina at Chapel Hill.
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Grant Support: This study was developed by the RTI-UNC Evidence-based Practice Center under contract to the Agency for Healthcare Research and Quality (290-97-0011).
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Requests for Single Reprints: Reprints are available from the Agency for Healthcare Research and Quality Web site (http://www.ahrq.gov/clinic/prevenix.htm) and in print through the Agency for Healthcare Research and Quality Publications Clearinghouse (800-358-9295).
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Current Author Addresses: Dr. Hayden: Division of General Medicine, Department of Medicine, 11C Ambulatory Care, Veterans Administration Medical Center.
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Dr. Pignone: University of North Carolina Division of General Internal Medicine, CB 7110, 5039 Old Clinic Building, University of North Carolina Hospitals, Chapel Hill, NC 27599-7110.
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Dr. Phillips: AFMOA/SGZZ, Population Health Support Division, 2606 Doolittle Road, Building 804, Brooks Air Force Base, TX 78235-5249.
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Dr. Mulrow: Department of Medicine, University of Texas Health Science Center at San Antonio, 7400 Merton Minter Boulevard (11C6), San Antonio, TX 78284.
- Copyright ©2004 by the American College of Physicians
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