Wendy Wolfson
RedwoodAge.com

Popping a baby aspirin a day cuts the risk of heart attacks and stroke, but raises the risk of internal bleeding. So should healthy people take one as they age?

Probably not, according to a new study that compared people who take aspirin daily to those who don't.

Aspirin is considered a cheap and benign treatment. It's been show to reduce the risk of heart disease and stroke by about a quarter for people diagnosed with vascular disease. However, it slightly raises the risk of bleeding into the gastrointestinal tract and the brain.

Some researchers have suggested that since age is a risk factor for heart and vascular disease, everybody past a certain age should take aspirin. But age is also a risk factor for bleeding.

Alternatively, a person could delay taking aspirin until some sign of vascular disease appears. Unfortunately, that sign could be a heart attack or stroke. On the other hand, doing nothing would prevent decades of slightly increased risk for bleeds.

"If you have some evidence of vascular disease that was caused by a blocked artery, then you have some net benefit," said Sir Richard Peto, professor of Medical Statistics & Epidemiology at the University of Oxford, and a study collaborator. According to Peto, if you are just an ordinary person who hasn't got any evidence of disease, aspirin still produces some reduction in the risk of an artery getting blocked. However, the benefit isn't large.

"And you still have the side effects," said Peto. "The alternative strategy is to wait or, if you want to do something, take something safer, like a statin or blood pressure-lowering medicine to reduce risk."

Studies Reviewed
The researchers looked at six primary prevention trials involving  95,000 healthy people, half of whom took aspirin long-term. In the course of  660,000 person-years, these low-risk people experienced 3,554 serious vascular events. The healthy people who took aspirin had a 12 percent proportional reduction in serious vascular events compared to the control group that didn't take it. This is mainly because they experienced a fifth fewer heart attacks.

However, they had slightly more strokes caused by a bleed into the brain. They also had slightly more gastrointestinal bleeds. They had no significant difference in the overall risk of vascular death.  

The researchers then analyzed 16 secondary prevention trials involving a total of 17,000 people who had already been diagnosed with vascular disease, half of whom took aspirin. Over 43,000 person years they experienced 3,306 serious vascular events.

In this high-risk group, those who took aspirin had significantly fewer vascular events than the control group (6.7 percent vs. 8.2 percent a year). Broken down, this meant a fifth less strokes (2.1 percent vs. 2.5 percent) and a fifth less heart attacks (4.3 percent vs. 5.3 percent).  In all groups, men and women seemed to experience the proportional reduction, regardless of age.  

The researchers concluded that the net benefits of taking a daily aspirin outweighed  risks for people who have already had a heart attack or a stroke that was caused by a blocked artery.

Healthy people, however, probably shouldn't take aspirin for prevention, as its benefits are counterbalanced by the slightly increased risk of bleeding.  The researchers  recommended further research on certain groups like diabetics.

The study by researchers from the Anti-Thrombotic Trialists' Collaboration was funded by UK biomedical research organizations and was published in "The Lancet."