Nearly a third of middle-aged Americans regularly take a baby aspirin in the hope of preventing a heart attack or a stroke or lowering their cancer risk. But new research shows that aspirin is not for everyone, and that in some patients this so-called wonder drug is doing more harm than good.
“I stop a lot more aspirin than I start,” said Dr. Alison Bailey, director of the cardiac rehabilitation program at the Gill Heart Institute at the University of Kentucky. “People don’t even consider aspirin a medicine, or consider that you can have side effects from it. That’s the most challenging part of aspirin therapy.”
Last week, researchers in London reported in the Archives of Internal Medicine that they had analyzed nine randomized studies of aspirin use in the United States, Europe and Japan that included more than 100,000 participants. The study subjects had never had a heart attack or stroke; all regularly took aspirin or a placebo to determine whether aspirin benefits people who have no established heart disease.
In the combined analysis, the researchers found that regular aspirin users were 10 percent less likely than the others to have any type of heart event, and 20 percent less likely to have a nonfatal heart attack. While that sounds like good news, the study showed that the risks of regular aspirin outweighed the benefits.
Aspirin users were about 30 percent more likely to have a serious gastrointestinal bleeding event, a side effect of frequent aspirin use. The overall risk of dying during the study was the same among the aspirin users and the others. And though some previous studies suggested that regular aspirin use could prevent cancer, the new analysis showed no such benefit.
Over all, for every 162 people who took aspirin, the drug prevented one nonfatal heart attack, but caused about two serious bleeding episodes.
“We have been able to show quite convincingly that in people without a previous heart attack or stroke, regular use of aspirin may be more harmful than it is beneficial,” said Dr. Sreenivasa Seshasai of the Cardiovascular Sciences Research Center at St. George’s, University of London.
The findings are likely to add to the confusion about who should regularly take aspirin and who should not.
Research shows that among men who have had a heart attack, regular aspirin use can be lifesaving, lowering the risk of a second heart event by 20 to 30 percent. It also reduces the risk of a recurrence among women who have had a stroke caused by a blood clot.
Aspirin works by interfering with the blood’s clotting action. In blood vessels narrowed by heart disease, fatty deposits can burst, leading to the quick formation of a clot that blocks the flow of blood to the heart or brain. Regularly taking an aspirin helps prevent the clot from forming.
In 2007, the United States Agency for Healthcare Research and Quality reported that 19 percent of Americans regularly took aspirin, including 27 percent of those ages 45 to 64 and about half of those 65 and older.
Yet many current aspirin users have never had a heart attack or stroke, and take aspirin in the hope of preventing one. Among middle-aged aspirin users, the 2007 report found, 23 percent didn’t have established heart disease. Among older aspirin users, 41 percent didn’t have a history of heart disease or stroke.
For people without heart disease, guidelines from the United States Preventive Services Task Force and other national groups say aspirin therapy should be decided case by case, depending on the individual’s risk factors and family history.
But Dr. Seshasai said the new findings didn’t necessarily mean that healthy men and women should immediately stop taking aspirin. People with a strong family history of heart attack or stroke may benefit by continuing the regimen, and they should raise the question with their doctors.
“The decision to treat such individuals with aspirin should be made on a case-by-case basis, taking into account the likely risk of heart attack or stroke in the future,” he said. “However, as the risk of major bleeding episodes increases proportionately with an increase in benefit, physicians and patients must make carefully considered choices regarding long-term aspirin treatment.”
But some experts say the problem is that not every doctor has caught up with the latest science, and many patients decide on their own to take aspirin.
“They hear aspirin is good, so they take an aspirin,” Dr. Bailey said. “They don’t think of it as something that could potentially cause harm.”
