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Cardiovascular disease is the leading cause of death in the United States, and low-dose aspirin used to be a go-to drug for trying to prevent a heart attack or stroke. But the advice on this is shifting, NPR's Will Stone reports.
WILL STONE, BYLINE: Primary care doctor Rebecca Hoffman is getting more questions about aspirin these days, especially from her older patients.
REBECCA HOFFMAN: You know, back in the day, it was standard stuff because they saw that it prevented the clotting.
STONE: Now her patients are seeing headlines about aspirin no longer being recommended for people over 60 who want to prevent a heart attack or stroke.
HOFFMAN: It hasn't been a great groundswell of protest, but there has been some interest why the guidelines changed.
STONE: Those guidelines are from the U.S. Preventive Services Task Force, and they're changing because the science has changed since the influential medical panel put out its last guidance in 2016. Salim Virani is a cardiologist at Baylor College of Medicine. He says newer studies are not finding as much of a benefit, in part because people are taking drugs like statins.
SALIM VIRANI: So aspirin's benefit has become marginal because we have these other therapies that reduce the risk of heart attacks or strokes, but the bleeding risk associated with aspirin therapy has persisted.
STONE: That risk of bleeding in the stomach, intestines and brain can be fatal, and it increases with age, which is why these guidelines against starting aspirin are strongest for those over 60. It's a closer call for people who are in their 40s and 50s. For them, it depends on their cardiovascular risk, and doctors can use a formula to help gauge that.
VIRANI: It's not a decision to be made at a pharmacy counter. I think we get sometimes a little bit carried away by the fact that it's over the counter, so it must be safe, and I would emphasize that that is not the case.
STONE: Aspirin helps prevent heart attack and stroke by making it harder for tiny bits of cells, known as platelets, to clump together.
ERIN MICHOS: And so by the same mechanism that it can prevent platelets clotting is the same mechanism that it could cause bleeding.
STONE: That's Johns Hopkins cardiologist Erin Michos. She stresses these new guidelines are not relevant to everyone, including the patients she's hearing from who already have cardiovascular disease.
MICHOS: They call my office and say, should I stop my aspirin? I'm like, no, no, you've had a bypass. You've had three heart attacks. You have - I mean, you know, stay on your aspirin.
STONE: For them, the risk of another heart attack generally outweighs the concerns of bleeding. What's also confusing is that the guidelines just focus on whether or not to start taking aspirin. They don't say what you should do if you're already on it. Michael Gaziano is a cardiologist at Brigham and Women's Hospital and the Boston VA.
MICHAEL GAZIANO: If you've been on aspirin for a long time, the risks are lower because the bleeding risk often occurs when you begin to start aspirin.
STONE: Now, there are things that can change your bleeding risk once you're on aspirin - for example, if you start taking other medications as well, like ibuprofen. Gaziano led one of the recent key trials on aspirin. He says the research isn't as cut and dry as the guidelines look. Some people have worrying scans, but they've not actually had a heart attack.
GAZIANO: Now, they're in the middle group, and we really don't know what to do with that group as much, but they're at probably higher than average risk.
STONE: And he says the strict age cutoffs can be arbitrary. They don't consider frailty or other medical conditions.
GAZIANO: This is a pretty complex risk-benefit calculus to do, and it's not one that I think a layperson can do in their kitchen.
STONE: The guidelines still need to be finalized, and Gaziano says the best advice, when in doubt, is to talk to your doctor. Will Stone, NPR News.
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