HEART
October 28, 2008

Aspirin, A Mixed Picture

Aspirin does not appear to prevent heart attacks, at least not in people who have never had one. And the risks remain.

According to a current study, aspirin does not lower the risk of having a first heart attack or stroke, even in high risk groups such as those with diabetes.

People who have diabetes are two to five times more likely to suffer from heart disease than the general population. The American Heart Association, The American Diabetes Association and the U.S. government recommend aspirin for people with diabetes and other high risk conditions, to prevent a first heart attack or stroke.

The subjects did not benefit from aspirin (or antioxidants).

A recent study headed by Dr. Jill Belch, and reinterpretation of older studies may change this. Dr. Belch is a professor of vascular medicine at the University of Dundee in Scotland.

Prevention of a first heart attack or stroke is often referred to as primary prevention. Prevention of a recurrence in those who have had a previous heart attack or stroke is called secondary prevention. There is no controversy over the fact that aspirin is effective in secondary prevention of these events.

Dr. Belch's study focused on aspirin's role in primary prevention. The 1,276 participants in the study were all over forty years old and either had diabetes or partial blockage of leg arteries. Both of these conditions predispose the subjects to cardiovascular problems, but no subject had previously suffered a heart attack or stroke. Since the study also tested the effect of antioxidants, participants either took aspirin or placebo, antioxidants or placebo, both aspirin and antioxidants or two placebos daily. After eight years, subjects' health was evaluated.

The subjects did not benefit from aspirin (or antioxidants). The number of heart attacks and strokes was exactly the same for those taking aspirin and those taking placebo. These findings appear in the October 16, 2008 online issue of the British Medical Journal. Dr. Belch's final words on aspirin are: "It works if you've already had a heart attack. But there is no proof for primary prevention, none at all."

Dr. Belch also discusses the meaning of five previous clinical trials of aspirin in her journal article. Those studies did show a positive effect from aspirin in preventing heart attack. But aspirin didn't improve the mortality of the participants (they didn't live longer). Because those studies also showed an increased risk of stroke and major bleeding from taking aspirin, none of them recommended giving aspirin to all people with diabetes for primary prevention of CV events, but only to specific subgroups − certain individuals.

Aspirin's role in causing gastrointestinal bleeding is the main reason that its usage is among the top ten causes of adverse drug events. The risk of bleeding increases with age and prolonged aspirin usage.

Dr. William R. Hiatt is a professor of Medicine at the University of Colorado. He wrote an accompanying editorial to Dr. Belch's article, which appears in the same issue of BMJ. His thoughts on aspirin: "Overall, if you do not have heart disease, the risk of bleeding outweighs any benefit you get from aspirin."

If aspirin has been prescribed to you to prevent a first heart attack, don't stop taking it; discuss this with your doctor. The studies mentioned here refer to generalized conditions and your specific condition may call for aspirin. Your doctor may have had very good reasons for prescribing it.

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