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Until not too long ago, doctors used to recommend the routine use of aspirin to prevent heart attack and stroke. This all changed after a number of major clinical trials found few benefits to this kind of practice. Meanwhile, daily aspirin use is associated with internal bleeding risks. In response to this new science, the American Heart Association and American College of Cardiology now recommends against the daily use of aspirin for people older than 70 or those with bleeding risk who don’t have any existing cardiovascular disease.

The benefit of taking aspirin for the majority of otherwise healthy adults just doesn’t outweigh the risks enough

Millions of people routinely use aspirin when they shouldn’t, according to a new study conducted by researchers at the Beth Israel Deaconess Medical Center (BIDMC).

“Although prior American Heart Association and American College of Cardiology guidelines recommended aspirin only in persons without elevated bleeding risk, the 2019 guidelines now explicitly recommend against aspirin use among those over the age of 70 who do not have existing heart disease or stroke,” said senior author Christina C. Wee, a general internist and researcher at BIDMC and Associate Professor of Medicine at Harvard Medical School.

“Our findings suggest that a substantial portion of adults may be taking aspirin without their physician’s advice and potentially without their knowledge,” she said.

For decades, aspirin — which costs pennies and doesn’t require a prescription — was considered an easy way to prevent a heart attack, stroke or other cardiovascular events for all people. But this assumption has been challenged by a string of new studies.

The new guidelines apply to people who don’t have known heart disease or stroke problems but who might consider taking aspirin to prevent heart attack or stroke in the first place. These recommendations do not apply to people who already have had a stroke or heart attack, or who have undergone bypass surgery.

“It’s sort of back to the Hippocratic oath. Our job is first, do no harm. That’s what has contributed to an evolution in how we think about aspirin in primary prevention,” said Dr. Daniel Muñoz, an assistant professor of cardiovascular medicine at Vanderbilt University Medical Center in Tennessee, and one of the members of the guideline writing committee.

In a new study, researchers analyzed data from the 2017 National Health Interview Survey (NHIS), a nationally representative survey of American households which was conducted before the release of the new guidelines. Strikingly, the analysis revealed that about a quarter of adults aged 40 years or older without cardiovascular disease took daily aspirin to prevent any heart disease in the future. That’s equivalent to 29 million people, of which 6.6 million did so without seeking a physician’s opinion.

What’s more, nearly half of adults 70 years of age or older without a history of heart disease or stroke reported taking aspirin daily.

“Our findings show a tremendous need for health care practitioners to ask their patients about ongoing aspirin use and to advise them about the importance of balancing the benefits and harms, especially among older adults and those with prior peptic ulcer disease,” said lead author Colin O’Brien, a senior internal medicine resident at BIDMC and fellow at Harvard Medical School.

“These findings are applicable to adults who do not have a history of cardiovascular disease or stroke. If you are currently taking aspirin, discuss it with your doctor to see if it is still needed for you,” said Stephen Juraschek, MD, PhD, a primary care physician at BIDMC.

The findings were reported in the Annals of Internal Medicine.