LONDON — Aspirin could save 40,000 more lives each year worldwide if more people at high risk of having a heart attack or stroke took it, doctors said last week.
An analysis of nearly 300 clinical trials of aspirin and other "anti-platelet" drugs that help to prevent blood clots confirmed that aspirin reduces heart attacks and strokes in susceptible patients.
But only about half of the people who could benefit from aspirin and anti-platelet therapy receive it.
"This study shows that aspirin is beneficial in an even wider range of conditions than previously believed," said Dr Colin Baigent of Britain's Medical Research Council (MRC), who led the study.
"If we could get those patients treated we could save an extra 40,000 lives a year," he told Reuters.
Aspirin and anti-platelet drugs are normally given to patients who have suffered a heart attack or stroke to prevent a recurrence.
But Baigent and his team found the treatment could also help prevent an initial heart attack or stroke in people at high risk because they suffer from diabetes, angina or a buildup of fatty deposits in the arteries.
"Although patients are getting it if they have had a heart attack or previous stroke there is a vast range of patients out there who haven't yet had such an event but who can be identified as high-risk," Baigent added.
He attributed the underuse of aspirin, one of the world's most popular drugs, to a lack of clear guidelines. Aspirin can also cause stomach problems such as bleeding and ulcers, which could also explain why it is not more widely used.
The study, reported in the British Medical Journal, is one of the largest international overviews of a disease treatment. It involved hundreds of trials with 200,000 patients.
The researchers found that aspirin and anti-platelet therapy reduced the risk of a serious heart attack or stroke by a quarter and of non-fatal heart attack by a third.
It also cut less serious strokes by a quarter.
Low-dose aspirin (75-150 milligrams daily) also seemed to be as effective as high doses for long-term treatments. Adding a second anti-platelet drug in some cases could also be helpful, but more research was needed into the strategy, Baigent added.
"We need to get the message out there that symptoms of some form of arterial disease are something that should prompt doctors to consider treatment," said Baigent.
But he added that aspirin was only suitable for people who were at increased risk of a heart attack or stroke because of a medical condition. People should always consult a doctor before taking the drug regularly.
Professor Sir Charles George, medical director of the British Heart Foundation, which funded the research with the MRC, said the study provided further proof that aspirin had major benefits for people at high-risk of heart attack or stroke.
"Aspirin is not an appropriate treatment for everyone, but it is important that all those who might benefit are actually offered it," he said in a statement.