March 5, 2024 — It's a widely held and long-held belief that swallowing a low-dose aspirin pill every day can prevent heart attacks and strokes.
Approximately 30 million Americans taking aspirin to prevent the first cardiovascular event (“primary prevention”), and Nearly 40% of people over 50 years oldapproximately 49 million people take aspirin for primary or secondary prevention after having a stroke or heart attack.
However, experts are beginning to question aspirin's effectiveness, prompting medical professionals to reevaluate aspirin's role in primary prevention.
In 2019, the American College of Cardiology/American Heart Association Primary prevention guidelinesAspirin, the newest available, is „infrequently used“ in some types of routine primary prevention. cardiovascular disease This is because there is no net profit. ”
This recommendation was made after weighing the benefits of aspirin use in primary prevention against the risks of brain and gastrointestinal bleeding.Results from three major clinical trials published in 2018 significantly influenced guidelines, according to cardiologists John W. McEvoy, MBBCh, is one of the guideline co-authors and a professor of preventive cardiology at the National University of Ireland in Galway.
„Our initial view of this evidence was that aspirin did not support a significant effect in preventing heart disease or stroke, and that the bleeding risks probably outweighed the benefits,“ he said. Stated.
However, the guidelines also „require every patient to make an individual decision about aspirin,“ McEvoy said. One size does not fit all. We never told anyone not to give aspirin. Because we felt there were high-risk patients who could benefit. ”
Recommendations based on age
The U.S. Preventive Services Task Force, a nongovernmental advisory group, is also considering aspirin's role in primary prevention. Task force updated in 2022 2016 recommendations following a systematic review of the evidence. The group said aspirin use has a „small net benefit“ for primary prevention of cardiovascular events, but only in adults aged 40 to 59 who have a 10% or higher risk of a cardiovascular event within 10 years. . The report recommended that adults over 60 not take aspirin, citing „no net benefit.“
In explaining its advice for older adults, the task force said the risk of gastrointestinal bleeding, cerebral hemorrhage, and stroke associated with aspirin increases with age.
Not many studies have been conducted on the issue of risks and benefits of aspirin use in older adults. but, Secondary analysis of data From one of the most important studies of 2018 American College of Cardiology/American Heart Association The guidelines indicate that while the risk of cerebral hemorrhage is significant in people over 70 years of age, there is no benefit of aspirin as primary prevention of stroke in this population.
All 19,114 participants in the study, conducted in Australia and the United States, were healthy people with a median age of 74 years. Half of them received aspirin and the other half received a placebo.
Aspirin did not produce a statistically significant reduction in the incidence of ischemic stroke (the most common type). However, patients taking aspirin had a significant increase in intracerebral hemorrhage compared to patients taking a placebo.
Lead author Dr. John J. McNeil, professor of epidemiology and preventive medicine at Monash University in Melbourne, Australia, said both cerebral hemorrhage and hemorrhagic stroke were more frequent in the aspirin group, and that more frequent falls in older adults increased the odds. said. of these events.
„Most of these bleeds occur in people who fall and hit their heads. We suspect that many of these people hit their heads when they fell.“
Reducing the risk of CVD
The first studies on the benefits of aspirin in primary and secondary prevention of cardiovascular disease were conducted decades ago. Anum Saeed, MD, assistant professor of medicine at the University of Pittsburgh and a cardiologist at the UPMC Heart and Vascular Institute, says some risk factors are now better controlled than in the past, making aspirin less effective. He said there may be. For example, there are now statin drugs that lower LDL cholesterol (bad cholesterol) and effective drugs to lower blood pressure, she said.
Said carefully weighs a patient's risk factors before starting aspirin for primary prevention. She said some people advised to take aspirin include people with high calcium levels in their coronary arteries, people with diabetes and high LDL cholesterol.
But she added that people are advised to control their risk factors before starting to take aspirin. She recommends lowering your blood pressure and cholesterol, exercising regularly, and improving your diet.
If they don't have risk factors for cardiovascular disease, she won't give them aspirin. If you're over 70, have significant risk factors, and have been taking aspirin for a while without problems, she recommends continuing to take it. But she monitors these patients closely, checking for any risk of falls, for example.
Similarly, McEvoy tries to manage patients' risk factors before discussing aspirin with them. He will say that if your risk of CVD is low, you don't need aspirin. For people over 70, he emphasizes the risks of aspirin even more.
Discontinuing aspirin may pose risks
Should older adults who have been taking aspirin for years continue taking it for primary prevention? That's a surprisingly difficult question to answer.
In a recent paper, McEvoy and his colleagues sought to address this question By examining the combined data From the 2018 aspirin trial. They found that among the 15% of study participants who were taking aspirin before the study, those who continued to take aspirin during the study had lower heart rates than those who were given a placebo instead. This means fewer people had seizures or strokes.
Several observational studies have found similar results, with people who take aspirin for primary prevention and then discontinue it having a slightly higher risk of cardiovascular events than those who continue taking it, McEvoy said. Thought.
Nevertheless, he constantly discusses the pros and cons of continuing to use aspirin with his elderly patients.
„Some patients have had no problems with aspirin, even though they have been taking it for years. They have no history of indigestion or gastrointestinal bleeding, and they have no history of indigestion or gastrointestinal bleeding, and they have no history of falls or other medications that may increase their risk. There are no risk factors for bleeding.
He talks to his patients before asking them to stop taking aspirin.
„I say, 'The evidence is mixed. The risk of bleeding increases as you get older, but we also know that aspirin can reduce non-fatal cardiovascular disease,'“ he said.
Some patients feel so strongly about their risk that they are more concerned about the risk of heart disease or stroke than the risk of bleeding. „In those patients, I don't necessarily have to stop them from taking aspirin,“ McEvoy says. „But I weigh the risk factors and tell them that if they have other risk factors, they may not need aspirin.“