Healthy living

Risks and benefits of taking aspirin to prevent heart attacks

Healthy adults risk internal bleeding

Healthy adults who take aspirin daily to prevent heart disease are at risk of internal bleeding, according to the results of a large study published in the online version of the Lancet.

Scientists from the University of Oxford analysed the results from six primary prevention studies where aspirin was used to prevent heart attacks and strokes occurring in healthy adults. They also studied aspirin use in a further sixteen secondary prevention trials, involving 17,000 people, where it was used to prevent repeat heart attacks and stroke in people with cardiovascular disease.

In the primary prevention studies, involving 95,000 healthy people at low/average risk of a heart attack, aspirin reduced the risk of a non-fatal heart attack by about 12 per cent, compared with people who took no aspirin. However, the small risk of internal bleeding due to aspirin was increased by a third.

This means that for every 10,000 people treated with aspirin, there were five fewer heart attacks, but three more cases of internal bleeding as well as one case of stroke per year.

In the secondary prevention studies, aspirin reduced the risk of a serious vascular event (heart attack, stroke) by 20 per cent. As the risk of a serious vascular event is much higher in people with existing cardiovascular disease, this resulted in 150 fewer vascular events for every 10,000 patients treated per year . Under these circumstances, the benefit of aspirin was found to clearly outweigh the risk of bleeding.

Lead scientist Professor Colin Baigent, from the Clinical Trial Service Unit at the University of Oxford commented:

"Aspirin is of clear benefit for people who already have cardiovascular disease, but the latest research does not seem to justify general guidelines advocating the routine use of aspirin in all healthy individuals above a moderate level of risk for coronary heart disease."

He also added:

"Drug safety really matters when making recommendations for tens of millions of healthy people. We don't have good evidence that, for healthy people, the benefits of long-term aspirin exceed the risks by an appropriate margin."

This article was published on Sun 31 May 2009

Image © Darren Green -

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