Aspirin may no longer be effective as cardiovascular treatment

A new paper in Family Practice, published by Oxford University Press, found that the widespread use of statins and cancer screening technology may have altered the benefits of aspirin use. Researchers concluded that aspirin no longer provides a net benefit as primary prevention for cardiovascular disease and cancer.
Nearly half of adults 70 years and older have reported taking aspirin daily even if they don't have a history of heart disease or stroke. Overall, an estimated 40% of adults in the United States take aspirin for primary prevention of cardiovascular diseases, making it one of our most commonly used medications
Researchers conducted the first review of aspirin's role in cardiovascular prevention 30 years ago, reporting a reduction in risk for both fatal and non-fatal heart attacks. Subsequent reports also found a reduction in cancer deaths for patients taking aspirin for five or more years, but no reduction in cardiovascular related deaths or strokes, and consistently displayed a significant risk of major bleeding complications.
Most of these aspirin trials were set in Europe and the United States and recruited patients prior to 2000. Since then, cholesterol-lowering drugs have gone into widespread use, accompanied by better management of hypertension, less tobacco use, and widespread adoption of colorectal cancer screening.
Researchers compared these older studies with four recent large scale trials of aspirin. Broadly, participants in the newer trials resembled the contemporary population that would use aspirin for primary prevention. In comparison, they were older, somewhat less likely to smoke, and more likely to have type 2 diabetes than patients in the older trials.
Like older studies, the recent trials of aspirin for primary prevention found no mortality benefit and a significant increase in the risk of major haemorrhages. However, they failed to find evidence for the two important benefits of aspirin: a reduction in the risk of cancer deaths and a reduced risk of non-fatal heart attacks. For every 1000 patients who took aspirin for five years there were four fewer major cardiovascular events but 7 more episodes of major haemorrhage and no change to overall cardiovascular mortality.
With the widespread use of statins and population wide cancer screenings today, aspirin may no longer reduce the overall risk of cancer death or heart attack when given as primary prevention.
"The good news is that the incidence of cardiovascular disease and colorectal cancer are decreasing due to better control of risk factors and screening, but that also seems to reduce the potential benefit of aspirin."


Taking a baby aspirin every day to prevent a heart attack or stroke should no longer be recommended to patients who haven't already experienced one of these events.
That's according to a new study published in Family Practice.
Nearly one-quarter of Americans over the age of 40 have reported taking aspirin daily even if they don't have a history of heart disease or stroke.
That's a problem, says study author University of Georgia researcher Mark Ebell.
As a physician and epidemiologist at UGA's College of Public Health, Ebell's work evaluates the evidence underpinning clinical practice and health behaviors. The current recommendation for taking aspirin as the primary form of heart attack or stroke prevention is limited to adults aged 50 to 69 who have an increased cardiovascular risk.
"We shouldn't just assume that everyone will benefit from low-dose aspirin, and in fact the data show that the potential benefits are similar to the potential harms for most people who have not had a cardiovascular event and are taking it to try to prevent a first heart attack or stroke," said Ebell.
Aspirin was first found to reduce the risk of fatal and nonfatal heart attacks 30 years ago, and subsequent studies found evidence that aspirin may also reduce risk of stroke and colon cancer.
But aspirin use has always carried risks, said Ebell, namely bleeding in the stomach and brain.
More recent studies have begun to suggest that potential harms of taking aspirin may outweigh the benefits by today's medical standards.
"If you look back in the 1970s and '80s when a lot of these original studies were done, patients were not taking statin drugs to control cholesterol, their blood pressure was not as well controlled, and they weren't getting screenings for colorectal cancer," said Ebell.
Ebell and his colleague Frank Moriarty of the Royal College of Surgeons in Ireland compared aspirin studies using patient data from 1978 to 2002 to four large-scale aspirin trials occurring after 2005, when statin use and colorectal cancer screenings had become more widespread.
They found that for 1,000 patients treated for five years, there were four fewer cardiovascular events and seven more major hemorrhages. Ebell was particularly alarmed by the number of brain bleeds experienced by aspirin users.
"About 1 in 300 persons who took aspirin for five years experienced a brain bleed. That's pretty serious harm. This type of bleeding can be fatal. It can be disabling, certainly," he said. "One in 300 is not something that the typical doctor is going to be able to pick up on in their practice. That's why we need these big studies to understand small but important increases in risk."
Ebell cautions people who are concerned about their cardiovascular risk, but who haven't had a heart attack or stroke, to talk with their doctors about other ways to prevent a major event.
These days, he says, treatment for blood pressure, cholesterol and diabetes are more aggressive, and the rate of other risk factors like smoking has dropped.
"There are so many things that we're doing better now that reduce cardiovascular and colorectal cancer risk, which leaves less for aspirin to do," he said.