Colourful polarised light micrograph of aspirin (acetylsalicylic acid) crystals

Crystals of aspirin, which has been shown to raise the risk of bleeding in the elderly. Credit: Karl Gaff/SPL

Medical research

A daily aspirin might not be what the doctor ordered

A drug taken regularly by half of US adults might raise the risk of serious bleeding.

Taking aspirin daily does not significantly prevent first-time cardiovascular disease in healthy elderly people — and might even be harmful.

Medical advice has long held that low doses of aspirin can reduce the risk of heart attacks and strokes. Starting in 2010, John McNeil of Monash University in Melbourne, Australia, and his colleagues enrolled 19,114 healthy people aged 65 or older in the United States and Australia in a comprehensive trial to investigate aspirin’s benefits. The researchers randomly assigned half of this group to take low-dose aspirin every day and the other half to take a placebo.

Almost five years later, the researchers found that, compared with people in the control arm, people who had taken aspirin were significantly more likely to have had a major haemorrhage, and that more had died of cancer. Aspirin-takers also had a similar rate of new cardiovascular disease as people who had taken a placebo.

The researchers say that the result was unexpected, given that previous studies had found aspirin to be protective against cardiovascular disease in high-risk patients, and they say that further research is needed.