A new study has called into question the widely-perceived wisdom that low-dose aspirin should routinely be used to prevent heart attacks and strokes.

The largest meta-analysis to date, published in The Lancet, notes that the use of low-dose aspirin in people without cardiovascular disease was “not justified”. The study, carried out by the Antithrombotic Trialist’s Collaboration group, funded by the UK Medical Research Council, the British Heart Foundation, Cancer Research UK, and the European Community Biomed Programme, found the modest benefit of aspirin was offset by an increase in the risk of major gastrointestinal and extracranial bleeds.

These findings were based on an analysis of data from 95,000 patients from six primary prevention, low-risk, trials and 16 secondary prevention trials (high-risk), involving 17,000 patients. It concluded that the use of aspirin in the lower-risk group was found to reduce non-fatal heart attacks by around a fifth, with no difference in the risk of stroke or vascular morbidity.

However taking aspirin also increased the risk of internal bleeding by around a third in the primary prevention trials. Colin Baigent of Oxford University, who led the study, said "we don't have good evidence that, for healthy people, the benefits of long-term aspirin exceed the risks by an appropriate margin."

Responding to the study, Ellen Mason, senior cardiac nurse at the BHF, said the study “provides further confirmation that in those without existing heart disease there is limited benefit from taking aspirin due to the risk of bleeding”. She added that for this reason, “it is better for doctors to weigh up the benefit and risk of prescribing aspirin on an individual basis, rather than develop a blanket guideline suggesting everyone at risk of heart disease is routinely given aspirin”.