Are healthy people taking aspirin to defend themselves against heart disease? The idea was controversial and medical advice was mixed.
However, a review of the scientific data on this topic on Tuesday showed that all benefits are negligible and that they are balanced by increasing the risk of bleeding.
Aspirin is a blood thinner and can prevent the formation of clots that can lead to heart or stroke. But aspirin also increases the risk of bleeding in the brain, stomach and intestines.
"When taking into account the totality of the evidence, the cardiovascular benefits associated with aspirin were modest and equally balanced with major bleeds," the report said. Journal of the American Medical Association.
In the meta-analysis, 10 previous studies involving more than 164,000 people with an average age of 62 years were examined.
Comparing users of aspirin with those who do not take aspirin, the researchers found "significant reductions" in stroke, heart attacks and deaths from cardiovascular diseases among those who took aspirin.
The use of aspirin was also associated with an increased risk of "large bleeding versus aspirin".
Statistically, the benefits were close to risk.
If 10,000 people without heart disease did not take aspirin for a year, 61 of them would have a heart attack or a stroke, explained Kevin McConvai, a professor of applied statistics at the Open University.
If 10,000 similar people took aspirin for a year, 57 would have a heart attack or a stroke.
"Only four fewer than 10,000, but it still has some significance given how serious the disease is and how serious are cardiovascular diseases," said McConvai, who was not included in the study.
Heart disease is the largest killer of people around the world, taking 17.9 million lives every year across the globe, one-third of all deaths, the World Health Organization says.
"The poor side is an increase in major bleeding events, including bleeding within the skull and brain, or major bleeding in the stomach or intestines," added McConvai.
In a group of 10,000 people who do not take aspirin, 16 would have such an event in a year, compared with 23 of those who took aspirin.
In other words, about seven major bleeds a year, which McConway described as a "significant increase," although the annual risk of bleeding "is still not high."
According to Jeremy Pearson, associate director of the British Heart Foundation, the meta-analysis "valued renews our knowledge, but does not change the present perspective."
"This confirms that the average risk of harm is greater than the benefits, so the guidelines should not be changed."
Aspirin is not recommended in Britain for the prevention of heart disease.
But in the United States, the US Preventive Services Task Force recommends "initiating a low-dose aspirin for primary cardiovascular disease prevention (CVD) and colorectal cancer in adults aged 50-59 with 10 years or more 10 years Risk of KVB not under increased with a bleeding risk, have a life expectancy of at least 10 years.
According to a recent study in adults in the United States, about half reported the regular use of aspirin.
Sean Zheng, a cardiologist at King's College Hospital and the lead author of the book PIT The report says the public may not understand that taking low-dose or baby aspirin carries significant risks.
"In my opinion, there is no room for routine use of aspirin in patients who are healthy," he told AFP.
"Maybe it's because it's at the counter and is described as baby aspirin, but in fact our data shows that there is a very real risk, and that should not be taken with the expectation that it is completely benign and safe."
The study also looked at the preventative benefits of aspirin for cancer, and found that "there is no overall connection between the use of aspirin and incidence or cancer mortality."
The review pointed to a study that revealed a 15% reduction in cancer-related mortality associated with the use of aspirin after five years of follow-up.
However, the same results were not repeated in another study, which was followed by nearly 500 patients for seven years.
"The findings of this study indicate that aspirin is associated with cancer outcomes neutral, without suggestion of harm or benefit from available current evidence," says PIT the report.