The new recommendations are in a report from the US Preventive Services Task Force.
- Women age 55 to 79 years old should take ASA to prevent strokes, providing the benefit outweighs the risk of ASA.
- Men age 45 to 79 years old should take ASA to prevent heart attacks, providing the benefit outweighs the risk of ASA.
These new recommendation are stronger than the 2002 ones from the same group. Along with these new recommendations, the experts present ways to estimate personal benefit and risk. The report is available on the AHRQ website.
How to Calculate Stroke Benefit
The benefit is reduction in stroke risk. Tables are provided to estimate how women may benefit from taking ASA (Report Figure 4). For example, among 65 year old women with a 5% 10-year stroke risk, eight strokes per 1000 women will be prevented by taking ASA.
To Determine Stroke Risk
You can determine your personal stroke risk using the an interactive calculator at the Western Stroke Organization (for the web address, look under “Clinical Considerations, Women). For example, a 65 year old woman with systolic blood pressure of 160 has a 5.2% risk of stroke over 10 years (‘systolic’ is the first set of numbers in a blood pressure reading). If she also is a smoker, the risk jumps to 8.8%.
For a man of the same age, same systolic blood pressure, and a smoker, the ten year stroke risk is almost 14%.
To Determine Heart Attack Risk and Benefit
You can determine your personal heart attack risk using the provided link to an interactive calculator at the Medical College of Wisconsin.
Benefit–heart attacks prevented–is provided in Figure 2 of the report. For example, a 65 year old non-smoking man with no special risks, LDL cholesterol 99, HDL cholesterol 45, has a 10% risk of a heart attack in the next ten years. Taking ASA by 1000 men in this risk profile will prevent 32 heart attacks in ten years.
Whether or not to take ASA depends on the downside–the risks of taking ASA–as well as the benefits. ASA use increases the risk of serious bleeding from the stomach and elsewhere in the gastrointestinal (GI) tract. The risk is increased in people who have bled once. Previous bleeding from the GI tract is associated with at least double the risk of bleeding from ASA.
The risk is increased four times over in people who concurrently take NSAIDS (Motrin, Aleve, Naprosyn, others). Uncontrolled hypertension increases bleeding risks. Taking warfarin (coumadin, others) is generally considered a contraindication to ASA (ASA should not be used with warfarin).
- Men have twice the risk of bleeding than women.
- Enteric coating on ASA has not been shown to reduce the risk of bleeding.
- There are special safety considerations for older people.
Other Benefits of ASA
Not included in the Task Force’s considerations are other potential benefits from ASA. It may reduce the risk of dangerous colon polyps; however, a recent study indicated it does not reduce the risk of death from colon cancer. (Journal of the National Cancer Institute 2009 (Feb 18); 101:256)
What to Do
The panel encourages shared decision making. Individuals should discuss their potential personal benefits and risks from ASA with their physician.