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Aspirin in the prevention of heart attacks - more data
(June 2004)

Healthful Life has not been willing to endorse aspirin for prevention of heart attacks in apparently healthy adults. We have not been fully convinced by the evidence for aspirin’s use and are concerned about the dangers of aspirin-induced bleeding, including bleeding into the brain. One of the chief proponents (who conducted one of the major studies) and his colleagues argue for its use in an article in the Archives of Internal Medicine, September 23, 2003. They review five randomized trials of aspirin and conclude that administration of aspirin to men and women with a 10 percent risk of heart attack in the next ten years would prevent 150,000 heart attacks per year (about a one-third reduction in the total number of first heart attacks).

Of the five trials, four supposedly support aspirin use. Aspirin dosage ranged from 75 to 500 milligrams a day. However, in two of the four, the decrease in first heart attacks was not statistically significant. Actually, for a variety of reasons, those two studies are not really supportive. If those two studies are removed, then there are two positive, one negative study. In regard to dangerous side effects, the risk of hemorrhagic stroke (which, fortunately, occurs infrequenty) is increased 60 percent in aspirin users, a figure that is of borderline statistical significance.

The investigators say there is no evidence that aspirin use decreases deaths from heart attacks or coronary heart disease, even though it does reduce the risk of first heart attack. They conclude that, in “apparently healthy men and women who are at increased risk of a first heart attack, the benefits (of aspirin) clearly outweigh the risks”.

Commentary: The authors do make a spirited case for aspirin use

But,

- It is hard to figure why aspirin would reduce the risk of a first heart attack by about one-third, but not reduce deaths from heart attacks or coronary heart disease.

- The authors continue to downplay the risk of hemorrhagic stroke. It is true that heart attacks occur much more frequently than bleeding into the brain, but it is also true that an approximately 33 percent reduction in non-fatal heart attacks is accompanied by a 60 percent increased risk of hemorrhagic stroke.

- The use of a 10 percent risk of a heart attack in the next ten years for deciding who should get aspirin is debatable. The biggest single variable in determining the risk of future heart attacks is age. If 10 percent risk in the next ten years is used as the criterion, every man over age 70 would be placed on aspirin just because of age. Some groups supporting aspirin use would use a criterion of 15 percent or 20 percent ten-year risk so nobody would be placed on aspirin solely because of age; increased risk would then require other risk factors, including high blood pressure, smoking, high cholesterol level, low blood levels of protective high-density lipoprotein cholesterol (HDL - good cholesterol).

Healthful Life is still concerned about the increased risk of bleeding with aspirin. However, we would agree the benefits of aspirin outweigh the risk if the score in the Framingham risk assessment indicates a 20 percent risk of heart attack in the next ten years.

Eidelman, R., et al. An update on aspirin for the primary prevention of cardiovascular disease. Archives of Internal Medicine. Vol 163 (September 23) Pgs 2000-2010. 2003.

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