Risks of Using Aspirin to Prevent Heart Attack Or Stroke Differ by Gender and Age

Newswise — Patients and clinicians should consider risk factors-- including age, gender, diabetes, blood pressure, cholesterol levels, smoking and risk of gastrointestinal bleeding-- before deciding whether to use aspirin to prevent heart attacks or strokes, according to new recommendations from the U.S. Preventive Services Task Force. These recommendations do not apply to people who have already had a heart attack or stroke.

The recommendations are published in the March 17 issue of the Annals of Internal Medicine. The Task Force reviewed new evidence from the National Institutes of Health's Women's Health Study published since the last Task Force review of this topic in 2002, including a recent meta-analysis of the risks and benefits of aspirin and found aspirin may have different benefits and harms in men and women. The Task Force found good evidence that aspirin decreases first heart attacks in men and first strokes in women.

The more risk factors people have, the more likely they are to benefit from aspirin. The Task Force recommends that men between the ages of 45 and 79 should use aspirin to reduce their risk for heart attacks when the benefits outweigh the harms for potential gastrointestinal bleeding. Women between the ages of 55 and 79 should use aspirin to reduce their risk for ischemic stroke when the benefits outweigh the harms for potential gastrointestinal bleeding. Ischemic strokes occur as a result of an obstruction within a blood vessel supplying blood to the brain and are potentially prevented by aspirin use. The risk of gastrointestinal bleeding with and without aspirin use increases with age and is twice as high in men as in women. Other risk factors for gastrointestinal bleeding include upper gastrointestinal tract pain, gastrointestinal ulcers, and using non-steroidal anti-inflammatory drugs.

The Task Force recommended against using aspirin to prevent either strokes or heart disease in men under 45 or women under age 55 because heart attacks are less likely to occur in men younger than 45 and ischemic strokes are less likely to occur in women younger than 55, and because limited evidence exists in these age groups.

People age 80 and older could benefit more than younger people from aspirin because of their higher risk of cardiovascular disease, but the harms are also greater because the risk of gastrointestinal bleeding increases with age. The Task Force could not find clear evidence that the benefits of using aspirin outweigh the risks in people 80 years or older. "The decision about whether the benefits of taking aspirin outweigh the harms is an individual one. Patients should work with their clinicians to look at their risk factors and decide if taking aspirin to lower their risk for heart attacks or strokes outweighs the potential risk of gastrointestinal bleeding," said Task Force Chair Ned Calonge, M.D., who is also chief medical officer and state epidemiologist for the Colorado Department of Public Health and Information.

Cardiovascular disease is the leading cause of death in the United States. It is the underlying or contributing cause in approximately 58 percent of all deaths. In 2003, 1 in every 3 adults had some type of cardiovascular disease. In adults over the age of 40, the risk of developing cardiovascular disease is 2 in 3 for men and more than 1 in 2 for women.

The Task Force could not find evidence about what the optimum dose of aspirin is to prevent heart attacks or strokes. Evidence shows benefits at a range of doses, and the risk of gastrointestinal bleeding may increase with the dose. A dose as low as 75 mg seems as effective as higher doses. Taking aspirin increases a person's chances of gastrointestinal bleeding, the sudden loss of blood or perforation of the digestive tract that can lead to hospitalization or death. Taking aspirin also increases the chance of a hemorrhagic stroke, or bleeding in the brain, which is different than the ischemic stroke that aspirin can prevent. In 2002, the Task Force strongly recommended that clinicians discuss aspirin use with adults at increased risk for coronary heart disease and that discussions with patients should address both the potential benefits and potential harms of aspirin therapy. The new recommendation provides more specific guidance about benefits and harms to specific age groups and gender-specific benefits and provides clinicians with information on how to estimate an individual's risks for heart disease or stroke. The U.S. Preventive Services Task Force is an independent panel of experts in prevention and primary care. The Task Force conducts rigorous, impartial assessments of the scientific evidence for the effectiveness of a broad range of clinical preventive services, including screening, counseling and preventive medications. Its recommendations are considered the gold standard for clinical preventive services.

Once the embargo lifts at 5:00 p.m., EDT, on March 16, the recommendations and materials for clinicians will be available on the AHRQ Web site at http://www.ahrq.gov/clinic/uspstf/uspsasmi.htm. Previous Task Force recommendations, summaries of the evidence and related materials are also available on the AHRQ Web site. Clinical information is also available from AHRQ's National Guideline Clearinghouse at http://www.guideline.gov.