Is taking a daily Aspirin a good idea?
I have been asked a lot lately about the recent draft recommendation from the United States Preventive Services Task Force that adults over 60 do not need to take a daily Aspirin. While this might be surprising to some, it is actually based on nearly a decade of research and is not really news to most medical people. But, before people start throwing away their medication, we should remember that there is a difference between people who are trying to prevent a heart attack and those who have already had one.
In the medical world, we make a distinction between primary prevention and secondary prevention. In primary prevention, you are trying to prevent a healthy person from getting sick, whereas in secondary prevention you are dealing with someone who is already sick and trying to prevent them from getting worse. In secondary prevention — people who have had a heart attack or stroke or some other form of vascular disease in the past — Aspirin therapy is clearly beneficial.
But many of the people taking Aspirin do not have prior cardiovascular disease. These primary prevention patients were probably told to start Aspirin at some point or might have even started it themselves because of the often-repeated maxim that everyone over the age of 50 should take a daily Aspirin. In the past, some studies did suggest a benefit for a baby Aspirin once a day. Studies like the Physicians’ Health Study and the Hypertension Optimal Treatment trial showed a benefit to daily Aspirin and are likely responsible for the common perception that people, especially those with risk factors, should be taking it for primary prevention.
But the reality is that these studies are decades old and the evidence base has not held up over time. More contemporary studies have not shown a benefit to daily Aspirin for primary prevention, and a 2009 meta-analysis by the Antithrombotic Trialists Collaboration as well as a more recent 2019 meta-analysis in JAMA both showed the benefit to Aspirin therapy was minimal and largely offset by the increased risk of bleeding.
It is important to remember that these studies are not suggesting that Aspirin does not work or that the prior evidence is wrong. But Aspirin does increase the risk of bleeding, and for most patients, the benefit they draw from Aspirin is too small to justify the risk. Patients with prior heart disease are at higher risk and therefore draw more benefit from it. But patients with no history of cardiovascular disease, even those with risk factors, are too low-risk to benefit.
It might seem curious to people that earlier studies showed a benefit while more recent studies did not. The reality is that the medical landscape was very different in the late 1980s and early ’90s. Most medications we use today did not exist back then and those in use were not that good by today’s standards. People smoked more and many were walking around with blood pressure, blood sugar and cholesterol values that were much higher than we consider normal today.
So it isn’t that Aspirin stopped working, or that the earlier studies were wrong. The reality is that people today are at much lower risk for heart disease and stroke than they used to be because we are now better and more aggressive at treating their risk factors. Patients are lower-risk today and simply draw much less benefit from a baby Aspirin, hence the USPSTF recommendation.
There might be some primary prevention patients who are at particularly high risk for whom the cardiovascular benefit of Aspirin outweighs the bleeding risk. But for the majority of people, this is not the case. Given that patients often complain about taking too many pills, if they are truly primary prevention patients, the daily baby Aspirin could be one pill their physicians can stop recommending.
(This article was originally published in the Montreal Gazette.)