Table 14. Estimates of Benefits and Harms of Aspirin Given for 5 Years to 1000 Persons with Various Levels of Baseline Risk for Coronary Heart Disease*

Benefits and Harms  Baseline Risk for Coronary Heart Disease over 5 Years†       1%  3%  5%  Total mortality  No effect  No effect  No effect  Coronary heart disease events (n)  1–4 avoided  4–12 avoided  6–20 avoided  Hemorrhagic strokes (n‡)  0–2 caused  0–2 caused  0–2 caused  Major gastrointestinal bleeding events (n§)      2–4 caused  2–4 caused  2–4 caused

* Estimates are based on a relative risk reduction of 28% for coronary heart disease events in aspirin-treated patients and assume that risk reductions do not vary significantly by age.
^† Nonfatal acute myocardial infarction and fatal coronary heart disease. Five-year risks of 1%, 3%, and 5% are equivalent to 10-year risks of 2%, 6%, and 10%, respectively.
^‡ Data from secondary prevention trials suggest that increases in hemorrhagic stroke may be offset by reduction in other types of stroke in patients at very high risk for cardiovascular disease (>10% 5-year risk).
^§ Rates may be two to three times higher in persons older than 70 years of age.



Summary of U.S. Preventive Services Task Force
The U.S. Preventive Services Task Force (USPSTF) found good evidence that aspirin decreases the incidence of coronary heart disease in adults who are at increased risk for heart disease. It also found good evidence that aspirin increases the incidence of gastrointestinal bleeding and fair evidence that aspirin increases the incidence of hemorrhagic strokes. The USPSTF concluded that the balance of benefits and harms is most favorable in patients at high risk for coronary heart disease (those with a 5-year risk >3%) but is also influenced by patient preferences.

US Preventive Services Task Force. Aspirin for the Primary Prevention of Cardiovascular Events: Recommendation and Rationale. Ann Intern Med. 2002;136:157-160.