Should you take a daily Aspirin? It depends …
Benefits are clear for some people, but for others, bleeding risk might offset benefits, Christopher Labos says.
A series of recent studies has made people ask whether acetylsalicylic acid, better known as Aspirin, really is beneficial for your heart. As most people know, Aspirin is fixture in the field of cardiology and is routinely prescribed to people with heart disease. However, it was a relatively late arrival to the field. The ISIS -2 study, which showed that giving patients Aspirin after a heart attack improved survival, was only published in 1988. Nevertheless, subsequent studies, and a large meta-analysis by the Antithrombotic Trialists Collaboration, showed that Aspirin prevented recurrent events and established it as the standard of care.
Although the use of Aspirin after a heart attack (what we term secondary prevention) has a very clear benefit, giving Aspirin to patients before they have a heart attack (primary prevention) is not as clear cut. Even back in 1988, some studies were equivocal about whether Aspirin was beneficial for patients without heart disease. Subsequent studies have been variable, although some did show a reduction in non-fatal events though no reduction in mortality. A meta-analysis found that the reduction in serious vascular events was minimal (less than 0.1 per cent) and largely offset by the increased risk of bleeding.
Thus, the current set of studies in the New England Journal of Medicine should not be entirely surprising. The first study looked at patients with diabetes but no history of heart disease. It found that while Aspirin decreased the incidence of major vascular events by about one per cent, this benefit was counterbalanced by a one per cent increase in the risk of bleeding.
The other two studies looked patients who were age 70 and above. These were significant studies because older patients are often under-represented in clinical trials. In the first of the two studies, daily Aspirin use had no effect on preventing heart attacks and increased the risk of bleeding, although the increase was fairly minor at two extra bleeds per 1,000 people.
The second of the two studies generated more headlines. Using the same patient population of patients older than 70 years, it found that daily Aspirin use increased the risk of dying by about one per 1,000 people. These excess deaths were not actually cardiac deaths but were, strangely enough, due to an excess in cancer-related deaths, which the authors of the paper said were “unexpected and should be interpreted with caution.”
The notion that Aspirin can precipitate cancer deaths is somewhat hard to believe. There is already some pretty compelling evidence that Aspirin can reduce the risk of colorectal cancer. Also just a few weeks after the papers were published, two studies came out suggesting Aspirin might decrease the risk of liver cancer and ovarian cancer. Although these observational studies are less compelling than the evidence for colon cancer, it seems pretty clear that, overall, Aspirin, if anything, decreases cancer risk rather than increases it.
There is a common and oft-repeated saying that everyone over 50 should take a baby Aspirin once a day. It is not entirely clear, to me at least, where this idea originated, but many people hold to it. For patients who have a history of heart disease or stroke, the benefit of Aspirin is fairly clear. However, for patients who have never head a heart attack of stroke, the benefit of daily Aspirin is more modest, possibly not clinically significant, and potentially offset by the risk of bleeding. Whether you should take a daily Aspirin is dependent on your cardiovascular risk, which depends on risk factors like age, diabetes, blood pressure, cholesterol and smoking status, and must be weighed against the risk of bleeding.
As with most things in medicine, deciding whether you would benefit from a daily Aspirin is not a simple yes or no question. It is much more complicated.