The Danger of Daily Aspirin

If you're taking a daily aspirin for your heart, you may want to reconsider.

For years, many middle-aged people have taken the drug in hopes of reducing the chance of a heart attack or stroke. Americans bought more than 44 million packages of low-dose aspirin marketed for heart protection in the year ended September, up about 12% from 2005, according to research firm IMS Health.

Now, medical experts say some people who are taking aspirin on a regular basis should think about stopping. Public-health officials are scaling back official recommendations for the painkiller to target a narrower group of patients who are at risk of a heart attack or stroke. The concern is that aspirin's side effects, which can include bleeding ulcers, might outweigh the potential benefits when taken by many healthy or older people. "Not everybody needs to take aspirin," says Sidney Smith, a professor at the University of North Carolina who is chairing a new National Institutes of Health effort to compile treatment recommendations on cardiovascular-disease prevention. Physicians are beginning to tailor aspirin recommendations to "groups where the benefits are especially well established," he says.

Other patients say they would stick with aspirin because of other benefits attributed to the drug; past research has suggested that regular aspirin may reduce the risk of colon cancer, for instance. Virginia Douglas, 64, a retired trade-association executive, takes aspirin a few times a week. In addition to the possibly reduced risk of stroke, Ms. Douglas hopes to avoid colon cancer, which affected her father and grandfather. "There's always a new study with a new recommendation," says Ms. Douglas, of Sacramento, Calif. "You have to do what's best for you."

In a separate analysis, published in medical journal Lancet last May, an international group of scientists reached a broadly similar conclusion as did the U.S. task force—that doctors may have been recommending aspirin too widely. "You really have to have a clear margin of benefit over hazard before you should be treating healthy people," says Colin Baigent, a professor at Oxford University who coordinated the Lancet analysis.

Still, the Lancet authors disagreed with the U.S. panel on some important details, particularly about who should be taking aspirin. The two groups examined evidence largely from the same studies of the drug, although the international team analyzed the data differently. In the end, the international team of scientists, unlike the U.S. officials, concluded that aspirin's effects on men and women were mostly the same.

Another disagreement between the two groups also emerged: The U.S. task force said that age is the biggest factor determining a person's risk of internal bleeding from aspirin. But the international team said other factors, such as diabetes and high blood pressure, also play a significant role. Unfortunately, the scientists noted, the same factors that increase patients' risk of bleeding also increase their risk of developing heart disease. This, in turn, can make it more difficult to calculate whether the benefits of aspirin would outweigh the risks of side effects.

The U.S. task force responded with a letter to the Lancet, defending its finding that men and women's results did appear different. There is a "wealth of evidence that men and women have different cardiovascular disease manifestations and respond differently to aspirin," the letter said. The panel also reiterated its position that bleeding risk is best parsed by age.

Amid the debate, some individual doctors are finding their own position. Rodney Hayward, who codirects a Veterans Affairs research center in Ann Arbor, Mich., says he's not convinced that aspirin's effects on men and women are so different. He says he continues to recommend aspirin for certain patients of both sexes with significant heart risk.