An aspirin a day could help stave off heart disease - even if you have no history of it, according to a new study.
Despite its link to internal bleeding, scientists found the benefits of the drug may outweigh the risks for many patients without known cardiovascular disease (CVD).
The findings could help identify such patients using a personalised benefit-harm analysis and help during discussions between doctors and patients.
Researchers in New Zealand sought to identify patients who would most likely benefit from aspirin treatment.
A team from the University of Auckland studied more than 245,000 people, aged between 30 and 79, without established CVD.
The net benefit of aspirin was calculated by comparing the number of major bleeds likely to be caused with the number of CVD events likely to be prevented over five years.
Scientists worked out the number of major bleeds the aspirin was likely to cause and subtracted the number of CVD events it was likely to prevent.
Results showed 21 per cent of women and 41 per cent men without CVD were likely to benefit from aspirin treatment for five years if a hospitalisation or death due to an acute CVD event was considered equivalent to a hospitalisation or death due to two major bleeds.
This reduced to 2.5 per cent of women and 12 per cent of men when hospitalisation or death due to an acute CVD event was considered equivalent to a hospitalisation or death due to one acute major bleed.
The research team said their findings, published in the Annals of Internal Medicine, may not apply to populations outside New Zealand.
They also highlighted the diversity of findings in several aspirin studies to conclude that making firm, evidence-based recommendations for aspirin use for primary prevention is difficult.
Participants over the age of 79 were not included in the analysis.