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Aspirin and bleeding - a somewhat worrying report
(January 2006)

Aspirin in low dosage is recommended for prevention of heart attacks and stroke. But, aspirin can also cause bleeding into the brain or intestinal tract. The issue has always been potential benefit versus potential risk. Proponents trumpet the benefits and tend to downplay the risk of major bleeding, emphasizing its infrequent occurrence. A recent article analyzes the bleeding risk among almost 200,000 patients enrolled in 31 trials. Aspirin dose was divided into three categories: low (less than 100 milligrams a day), moderate (100 to 200 milligrams a day), actually still a pretty low daily dosage, and high (over 300 milligrams a day). Major bleeding (into the brain or intestinal tract) occurred in 1.5 percent of those given the low or "moderate" doses and 2.5 percent of those given more than 200 milligrams daily. When all bleeding episodes, major and minor, were analyzed, some bleeding occurred in almost 4 percent of those given less than 100 milligrams a day and in about 10 percent of those given higher doses.

Most of the patients evaluated were given aspirin either for severe heart pain (angina) or a heart attack, so the results may not be applicable to people given low-dose aspirin who are prescribed aspirin because they are considered to be at moderate or high risk of heart attack or stroke (but have not experienced either a heart attack or stroke). Nevertheless, these are sobering data. A large percentage of otherwise healthy persons (albeit with risk factors such as high blood pressure, elevated blood cholesterol level, cigarette smoking) who are given aspirin to prevent heart attack or stroke have a 10 to 20 percent likelihood of either heart attack or stroke in the next ten years. That means that 80 to 90 percent are not going to suffer such an event. For those individuals, a risk of major bleeding of 1.5 to 2.5 percent is a real worry. Healthful Life has been quite cautious in regard to recommending aspirin as a preventive. If an individual suffers a minor stroke (transient ischemic attack TIA), the risk of developing a major stroke is large enough to justify aspirin as a preventive. If an individual, according to the well-respected Framingham Score, is found to have at least a 20 percent risk of heart attack in the next ten years, the low-dose aspirin is reasonable to help reduce risk of non-fatal heart attack by about 25 percent, but its usefulness is not fully proved and it is not clear whether the risk of a fatal heart attack is reduced at al;. An alternative to aspirin in these high-risk individuals is to vigorously attack the major risk factors (high or high normal blood pressure, elevated blood cholesterol level - or its dangerous component low-density lipoprotein cholesterol [LDL]); low blood levels of protective high-density lipoprotein cholesterol [HDL]; smoking, and obesity, especially more than 30 percent above ideal weight).

The most important message is that there are no free rides; even low-dose aspirin carries a significant risk of severe bleeding, including bleeding into the brain. Consequently, use of aspirin for prevention of heart attack or stroke should be undertaken only after a lot of careful thought.

Serebruany, V.L., et al. Analysis of risk of bleeding complications after different doses of aspirin in 192,036 patients enrolled in 31 randomized controlled trials. American Journal of Cardiology. Vol 95 (May 15) Pgs 1218-1222. 2005.

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