Why the ‘Daily Aspirin’ Hype Is Over

The drug’s serious downsides prompt new guidelines. But are people getting the message?

Photo: Grace Cary/Moment/Getty

NNew research and guidelines have overturned decades of common wisdom on aspirin, bringing clarity to who should and should not take a daily low dose to prevent heart attacks and strokes. Yet millions of people pop the pills routinely for protection, often without advice from a doctor and even though it may be doing them more harm than good.

For people with a history of heart disease, aspirin is still commonly recommended as part of a treatment plan. But the medical community has changed its position on whether people who haven’t had heart problems should take the drug daily as a preventive measure.

Based on multiple studies done in 2018, the American Heart Association and American College of Cardiology issued new guidelines in March 2019 for daily low-dose aspirin use. It’s now advised mostly for people who are known to have heart disease, and only when prescribed by a physician who can run a suite of tests and best determine dosage, along with consideration of other treatment options ranging from exercise and improved diet to other medications, including blood thinners and statins, which lower cholesterol.

“If you’ve never had a heart attack or stroke, you likely should not be taking aspirin to prevent them.”

Otherwise, daily aspirin use should be avoided by healthy people, young or old. “It may actually cause more harm than good,” the panel of 18 experts concluded.

Paul Fritsch, a researcher at the University of Alberta in Canada, and his colleague Michael Kolber, a family medicine professor at the University of Alberta, recently reviewed the same research, and published similar findings in July in the Canadian Family Physician journal. They offer this advice: “If you’ve never had a heart attack or stroke, you likely should not be taking aspirin to prevent them.”

The European Society of Cardiology has not recommended aspirin for prevention of cardiovascular disease in people with no history of it since 2007, formalizing that advice in 2012, according to Massimo Piepoli, an Italian cardiologist and co-author of the group’s most recent guidelines.

To grasp why medical groups are now offering more conservative advice, it helps to understand the function of platelets, tiny plate-shaped cells in the bloodstream. When a blood vessel is damaged by an external or internal wound, platelets get a signal to rush to the spot, where they grow sticky, octopus-like tentacles that create a blood clot, plugging the wound to stop the bleeding. That’s usually good. But it’s bad if you have atherosclerosis, a narrowing of the arteries caused by buildup of fatty deposits. When part of a fatty deposit breaks off, as they are prone to do, platelets do their usual work, creating a clot. But a clot in an already narrowed artery can severely restrict or even block the blood flow to the heart or brain, causing a heart attack or stroke.

Aspirin inhibits the function of platelets, so doctors often prescribe a low dose — typically around 80 milligrams a day — to people diagnosed with atherosclerosis or who have had a heart attack or stroke. That dosage has been shown to reduce the risk of subsequent clots and decrease the risk of death. But there’s a downside: Anyone who takes aspirin, even in low doses, faces the risk of increased bleeding, particularly in the gastrointestinal tract.

“These aren’t nosebleeds or bleeding gums,” says Fritsch. “These are major internal bleeds where the patients need hospitalization and perhaps a blood transfusion.”

The bleeding risk has been known for more than a century, but only last year did it become clear in which situations the benefits of aspirin outweigh the risks, causing health groups like the American Heart Association to amend their recommendations.

Meanwhile, scientists and health professionals are battling the common perception of aspirin as a wonder drug, fueled by outdated science, industry marketing, and public misperception.

“Many individuals without established heart disease overestimate the benefits they might be getting from aspirin and don’t realize the risks,” says Erin Michos, an associate professor of medicine and epidemiology at Johns Hopkins School of Medicine and one of the authors of the new guidelines. “I think marketing played a big role. But also, many people think that because you can buy something over the counter that it is pretty safe, but that is not necessarily true at all.”

How did we get here?

The roots of aspirin trace back more than two millennia. Ancient Egyptians and Sumerians, along with the Greeks, used willow bark and leaves for pain relief. In the late 1800s, a chemist figured out the active ingredient, salicylic acid. By 1915, aspirin became available as a tablet without a prescription, and researchers were aware of the side effects: nausea, vomiting, and bleeding.

In the 1970s and ’80s, several clinical trials showed aspirin could reduce the risk of heart attacks in people who already had a history of coronary heart disease, explains Michos. Research back then also indicated aspirin could lower the risk of a first, or primary, cardiovascular event, leading to guidelines that “recommended aspirin for the primary prevention of cardiovascular disease for individuals at higher estimated risk,” Michos says. “And many healthy adults started taking aspirin for this reason. Many did so without the advice of their physicians, based on direct-to-consumer advertising.”

Serious seeds of doubt about aspirin’s unqualified heart benefits were sowed in 2009. A review of all the pertinent research, published in the journal Lancet, confirmed that taking aspirin after a person has a heart attack or stroke prevented them from having another. But the study questioned whether taking daily aspirin for the prevention of a heart attack in someone who hasn’t had a heart problem before outweighs the risks for bleeding.

Those doubts were confirmed last year in three clinical trials that examined the risks and benefits of aspirin. One of these trials followed 19,114 healthy people ages 65 and up who had no previous cardiovascular events, for an average of 4.7 years. One group took a low dose of aspirin daily; the other group was given placebos.

During the study, 5.9% of the people taking aspirin died, and 5.2% taking the placebo died. The higher death rate in the first group was due mostly to cancer. “The increase in cancer deaths in study participants in the aspirin group was surprising, given prior studies suggesting aspirin use improved cancer outcomes,” study team member Leslie Ford of the National Cancer Institute said in a statement.

Here was a key finding: Significant bleeding — in the brain and in the gastrointestinal tract — occurred in 361 people (3.8%) on aspirin and in 265 (2.7%) taking the placebo, the researchers wrote in the New England Journal of Medicine. However, among the people taking aspirin, 448 experienced fatal or nonfatal heart attacks, strokes, or other cardiovascular events during the study, compared to 474 people in the placebo group — which the researchers determined as too close to declare a clear benefit for daily aspirin, especially given the bleeding risk.

“The use of low-dose aspirin as a primary prevention strategy in older adults resulted in a significantly higher risk of major hemorrhage and did not result in a significantly lower risk of cardiovascular disease than placebo,” the researchers concluded. “Aspirin did not prolong healthy, independent living (life free of dementia or persistent physical disability).”

Two other clinical trials, one following people with moderate cardiovascular disease and another following people with diabetes, reached similar conclusions. These results prompted a realization that the science on aspirin use for heart event prevention had evolved from where it was previously. In the past, “when smoking was much more common, there was less control of blood pressure, and suboptimal cholesterol management with less use of statin medications, like there is today,” Michos says. “Medicine and science are constantly evolving, there are new scientific trials always being conducted, and guidelines are updated to keep up with the new science.”

Changing habits

Getting the word out may take some time. In July 2019, researchers revealed that about a quarter of Americans 40 years or older without cardiovascular disease say they take daily aspirin. Among them, some 6.6 million people were doing so without a physician’s recommendation.

The data, based on a nationally representative survey, is from 2017 — before the new guidelines were put in place — so it’s not clear how much things have changed since.

“Patients should discuss with their health care providers whether aspirin is right for them.”

The new U.S. guidelines stress the importance of consulting a doctor before starting or continuing (or discontinuing) any aspirin regimen. Michos emphasizes that the guideline revisions apply mostly to healthy people. “If someone has already had a heart attack, a coronary bypass or coronary stent, or a prior stroke, aspirin is still recommended for them,” she says. “These patients should not be stopping aspirin without discussing with their doctors.”

In her own medical practice, Michos has taken her patients with no known heart disease off aspirin.

But she still considers it for some people without a history of heart disease but who smoke or have a strong family history of early heart disease, or who have very elevated cholesterol or exhibit preclinical signs of atherosclerosis.

“It is a very fine line with aspirin with a narrow therapeutic window,” Michos says. “Patients should discuss with their health care providers whether aspirin is right for them.”

Explainer of things, independent health and science journalist, author, former editor-in-chief of LiveScience and Space dot com.