Major Australian research on the use of mini aspirins to prevent heart attacks and strokes is likely to change global guidelines on the use of this drug in healthy older people.
In three papers published in the prestigious New England Journal of Medicine today, the research revealed a low, 100mg, daily dose of aspirin was not beneficial for healthy people over 70.
Millions of people around the world take an aspirin to stave off the onset of heart disease, stroke and possibly other conditions.
Many of them have never had a heart attack or stroke and it has never been known whether aspirin, which has been around for more than 125 years, would be helpful.
No benefit to healthy older people
The new research has definitively shown that in older healthy people, aspirin does not prolong life, prevent or delay dementia or physical disability among participants, or substantially reduce their risk of heart attack and stroke.
Rather, those who took it were at a small increased risk of significant bleeding. They also had an unexpected small increase in deaths, mainly from cancer, which the researchers say should be taken with caution as it may be a chance finding.
Other large studies have suggested aspirin may prevent cancer over the longer term. As this benefit takes longer to manifest than the duration of the study, participants will continue to be followed up.
This joint Australian-US research with 19,000 participants mostly over the age of 70, was the biggest aspirin trial ever conducted and took seven years to complete.
About 16,700 participants were Australian, making this the largest prevention trial ever conducted in the country.
Aspirin has been shown to provide some protection for those who already have cardiovascular disease and want to prevent a second event. This is called secondary prevention.
But the big question has been whether it is good for primary prevention in healthy people, with no cardiovascular disease.
People over 70 were selected because they have the highest underlying risk of disease and if aspirin has a beneficial effect, it would most likely manifest among them.
They are also at an age when side effects are greatest.
“Outstanding” is how Professor Garry Jennings of the University of Sydney and executive director of Sydney Health Partners, describes the research.
He told the Science Media Centre its message was simple: “Most people with a history of heart or vascular disease will be advised by their doctor to take regular low-dose aspirin. Those without a history generally need not.”
While aspirin helps prevent clots, it also increases the risk of bleeding. The research shows in healthy older people, the odds are tipped towards bleeding risk.
Professor Jennings says this research provides conclusive evidence that can now be used to save lives and prevent needless bleeding complications, including stroke.
The answer can now be boiled down to a simple proposition: “If you are elderly and don’t need it, don’t take it,” says principal investigator, Professor John McNeil, head of the School of Public Health and Preventive Medicine at Monash University.
While it is estimated less than 10 per cent of Australians over 70 take a daily aspirin, the figure in America is almost 40 per cent.
Professor McNeil recommends people consult their doctor before considering stopping or starting a daily aspirin.
He says it has been obvious since the 1990s that there was a need for a trial of aspirin for primary prevention in people over 70.
As funding for major trials typically comes from the pharmaceutical industry, and as aspirin is off patent, a study could be done only with public funds.
“It is to the great credit to the US National Institutes of Health and the Australian National Health and Medical Research Council who recognised this need and underwrote the substantial cost of undertaking a study of this magnitude.”