New York - Does aspirin help healthy people live longer? Despite a lot of excitement about the common drug, scientists can't seem to agree.
One month after a study found that aspirin didn't appear to cut the risk of strokes or dying from heart disease but did lower the risk of heart attacks in healthy people, a report based on the same data has arrived at the opposite conclusion.
“Aspirin prevents deaths, myocardial infarction and ischemic stroke, and increases hemorrhagic stroke and major bleeding when used in the primary prevention of cardiovascular disease,” wrote researchers led by Nina Raju from the Prince Charles Hospital in Brisbane, Australia.
“This reduction in all-cause mortality tilts the balance between the benefits and risks of treatments in favour of the use of aspirin,” they said in the American Journal of Medicine.
Experts agree that aspirin, one of the world's most widely-used drugs, is worth taking for people who have already had one heart attack. While it has side effects, it lowers the chance of a second heart attack enough to outweigh those risks.
But whether and when healthy people might benefit remains a hotly debated question.
The recent study, which looks at all-cause mortality - or deaths for any reason - is a meta-analysis that pools the results of nine previous aspirin trials. The trials involved more than 100,000 men and women, and lasted four to 10 years.
Some participants were healthy and some had diabetes, but none had chest pain or other symptoms of an ailing heart.
According to the authors of the report, 3.65 percent of the people randomly assigned to take small doses of aspirin died during the trials, compared to 3.74 percent of people not taking the drug.
The researches said that difference is enough to favour aspirin use in people without a history of heart disease, and should inform future guidelines.
But a closer look at the data shows 1,111 people would need to take aspirin daily for the duration of the trials to stave off just one death - the so-called “number needed to treat.”
There is a price tag, too - nine of those individuals would suffer bleeding ulcers due to the aspirin, and nearly four would have other major bleeds, like hemorrhagic stroke.
“The number needed to harm is much, much lower than the number needed to treat,” said Franz Messerli, who heads the high blood pressure program at St. Luke's-Roosevelt Hospital in New York and was not involved in the recent study.
“If the patient has no risk factors for heart disease, I see no reason to put them on aspirin.”
Messerli also said the reduction in deaths is barely credible statistically speaking, and that the analysis differs from a previous one based on the same nine trials.
“That's what bothers me. One says the effect is statistically significant and the other says it's not,” he said. “Why the heck that would be, I don't know.”
The previous meta-analysis was supported by aspirin-maker Bayer, while the new one received no funding.
The researchers did find some clear-cut benefits, though.
For instance, 1.68 percent of people on aspirin suffered a heart attack, fatal or non-fatal, compared to 1.91 percent of those not taking the drug.
That means about 435 people would have to take an aspirin daily to prevent one heart attack.
The US Preventive Services Task Force (USPSTF), a federally-supported expert panel, advises that men age 45 to 79 take aspirin to stave off heart attacks if the benefit outweighs the risk of bleeding. For women age 55 to 79, aspirin is recommended to prevent strokes, with the same caveat.
“The number of events that you prevent depends on your baseline risk. A blanket recommendation that everybody should take an aspirin is not a good idea,” said Michael LeFevre of the USPSTF to Reuters Health last month. - Reuters