TAMPA • Should healthy people take aspirin to ward off heart disease?
The notion has been controversial and the medical advice mixed. But a review of scientific data on the topic showed that any benefits are slight and counterbalanced by a matching rise in bleeding risks.
Aspirin is a blood thinner and can help prevent clots that may lead to heart attack or stroke. But it also boosts the risk of haemorrhage in the brain, stomach and intestines.
"When considering the totality of evidence, cardiovascular benefits associated with aspirin were modest and equally balanced by major bleeding events," said the report by researchers at King's College Hospital in London.
The study was published on Tuesday in the Journal of the American Medical Association (Jama). The meta-analysis examined 10 prior studies involving a total of more than 164,000 people with an average age of 62.
The researchers compared aspirin users to those who do not take aspirin and found "significant reductions" in strokes, heart attacks and deaths from cardiovascular disease among those who took it.
Aspirin use was also linked to an increased risk of "major bleeding events, compared with no aspirin", it said.
Statistically, the benefits were close to the risks.
If 10,000 people without heart disease took no aspirin for a year, 61 of them would have a heart attack or stroke, explained Professor Kevin McConway, emeritus professor of applied statistics at The Open University.
If 10,000 of these people took aspirin for a year, 57 of them would have a heart attack or stroke. "Only four fewer in 10,000, but that still has some importance, given how common such diseases are and how serious cardiovascular disease is," said Prof McConway, who was not involved in the study.
Heart disease is the top killer of people worldwide, taking 17.9 million lives around the planet each year, amounting to one-third of all deaths, says the World Health Organisation.
"The downside is the increase in major bleeding events, including bleeding inside the skull and brain or major bleeds in the stomach or gut," added Prof McConway.
In a non-aspirin-taking pool of 10,000 people, 16 would have such an event in a year, compared with 23 among aspirin-takers.
In other words, about seven more major bleeds annually, which Prof McConway described as a "substantial increase", even though the annual risk of a haemorrhage "is still not high".
According to a recent nationwide survey of US adults, about half reported regular aspirin use.
Dr Sean Zheng, a cardiologist at King's College Hospital in London and lead author of the Jama report, said that the public may not understand that taking low-dose, or baby aspirin, carries significant risks.
"In my opinion, there is no place for routine use of aspirin in patients who are healthy," he said.
"Maybe it's because it's over the counter and it's described as a baby aspirin, but actually, our data shows that there is a very real risk and you shouldn't take it with the expectation that it's completely benign and safe."
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 low-dose aspirin use for the primary prevention of cardiovascular disease (CVD) and colorectal cancer in adults aged 50 to 59 years who have a 10 per cent or greater 10-year CVD risk, are not at increased risk for bleeding and have a life expectancy of at least 10 years".