Do healthy people need an aspirin a day?
If you are having a heart attack, chewing a full-strength aspirin tablet can be a lifesaving move. If you have heart disease, have had a heart attack or stroke, or are at very high risk for having one, taking a low-dose aspirin every day is part of a proven strategy for preventing one of these life-changers. But what if you are relatively healthy? Will taking aspirin help you?
Aspirin makes blood clot less easily. Since blood clots can trigger heart attacks and strokes, this effect of aspirin is welcome. Unfortunately, however, by making blood clot less easily aspirin also can cause bleeding, including serious bleeding (hemorrhage) of stomach and intestinal ulcers or, most seriously, bleeding inside the brain (hemorrhagic stroke). Such hemorrhages can be deadly.
It's the balance of benefits and risks that guides who should take aspirin for primary prevention — preventing heart attack, stroke, or another manifestation of cardiovascular disease in seemingly healthy people.
Researchers from six large primary prevention trials of aspirin pooled their data and analyzed them as if they were from a single large trial, using a technique called meta-analysis. In this relatively healthy group of 95,000 volunteers, the reduction in heart attacks and strokes in people taking aspirin was almost counterbalanced by major bleeding in the gastrointestinal system and the brain (The Lancet, May 30, 2009). The researchers concluded that for individuals without previously diagnosed cardiovascular disease, "aspirin is of uncertain net value."
Another meta-analysis showed only a modest overall benefit, if any, for aspirin among people with diabetes but no cardiovascular disease, and it had little impact on heart attack or stroke (BMJ online, Nov. 6, 2009).
Finding the tipping point
Don't take aspirin just because you've heard it can help prevent a heart attack or stroke. It can, but it can also do some damage. Here is a rule of thumb. If you are healthy, haven't been diagnosed with heart disease or other cardiovascular disease, and don't have risk factors for them, aspirin probably isn't for you. The less healthy your heart and arteries, the more likely the advantages of taking aspirin will outweigh any risks. So talk to your doctor about whether the benefit of taking regular aspirin is likely to bring more benefits than risks.
March 2010 update