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When an older woman arrived at a Cambridge medical clinic recently, Dr. Sarah Stoneking was surprised to learn that the patient was taking an aspirin every day.
The patient was nearly 80, and didn't have a clear reason to take the medication. Aspirin in general, and especially in older patients, can have a lot of side effects, including serious bleeding.
Stoneking, an internist and also my colleague, suggested her patient stop taking the daily aspirin, but the woman refused. She thought aspirin "was a panacea," Stoneking recalled, one that protected her from the strokes and heart disease that had affected most of her friends. "She took it religiously," Stoneking said.
When I started residency three years ago, the benefits of aspirin, specifically 81-mg baby aspirin, seemed clear. Even the U.S. Preventive Services Task Force (USPSTF), a top panel of experts that issues guidelines, endorsed low dose aspirin for large swaths of the population: men aged 45-79, and women aged 55-79, who were not at high risk for bleeding or other side effects. In other words, about a quarter of the population could benefit from a daily aspirin. And recently, reports have suggested that aspirin may even prevent cancer.
But new recommendations from the USPSTF, published last month in the Annals of Internal Medicine, recommend aspirin for far fewer people. The guidelines say aspirin may benefit men and women, aged 50-59, who have a 10 percent or greater chance of having a heart attack or stroke in the next 10 years because of their risk factors for heart disease (such as uncontrolled diabetes, high blood pressure and smoking). Even for this population, the evidence for aspirin has been downgraded from “high” to “moderate” certainty.
This is the kind of thing that drives patients crazy. Millions of people take an aspirin every day, thinking they are doing something positive to protect their hearts. Now, we physicians are back-tracking on those recommendations. What gives? This may feel like a flip-flop to patients, but it's really a refinement in our recommendations; a reflection of new and better data.
The bottom line is aspirin "has benefits, but it also has harms, and the harms are important to understand,” says Dr. Kirsten Bibbins-Domingo, a professor at the University of California, San Francisco, chair of the USPSTF and co-author of its most recent aspirin guidelines.
Over the last six years, she says, new studies are helping to quantify the harms of aspirin. Those harms include internal bleeding, usually in the stomach, and, more rarely, in the brain. For those under 50, the benefits were not as clear, the USPSTF found. For people 60 and older, the risks were higher than previously understood. The updated guidelines, she said, support the concern “that too many people take aspirin.”
Dr. T. Jared Bunch, a cardiologist at Intermountain Healthcare in Salt Lake City, Utah, agrees. He sees a number of patients who take aspirin because they think it will protect them from heart disease, often without discussing this with their providers. His message: "Aspirin is a medication, and it needs to be viewed that way… If you don’t need to take it, don’t take it.”
Some researchers, like Dr. JoAnn Manson, a physician-researcher at Brigham and Women’s Hospital, believe that these recommendations leave too many people out. She is concerned that for men and women with moderate risk for heart disease there may be some benefit, and that the guidelines “really did not fully address how to handle that group.” For these patients, she says, the evidence is "quite strong" that even those at moderate cardiovascular risk may benefit from aspirin. Specifically, she says, this group includes men in their 50s and women over 65.
In addition to the benefits aspirin has for heart disease, there is growing evidence that it could prevent cancer, particularly colon cancer. Researchers like Dr. Andrew Chan at Massachusetts General Hospital, believe that aspirin could be used to prevent cancer generally: according to a 2016 study he co-authored in the Journal of the American Medical Association Oncology, regular use of aspirin could prevent nearly one in 50 cancers.
As a clinician, Chan says, he understands that the decision to recommend aspirin is complex. But with so many potential benefits, he thinks that “it would be a shame for us to be paralyzed by inaction” and not discuss aspirin with patients. “I think the public health impact [of aspirin] can be substantial” he said.
The researchers were all in agreement, however, that people should not be taking aspirin without speaking to their medical provider. Many people seem to think they can choose to take aspirin or not because it is over the counter, and there is a strong belief that “anything over the counter is safe” Manson said.
So to help you have the conversation with your doctor, here's what most experts agree on:
- If you have had a heart attack or stroke caused by a clot, you should probably take an aspirin unless you have compelling reasons not to.
- If you are 50-59, and are at high risk for a first heart attack or stroke, you will probably benefit from 81 mg of aspirin if your risks of bleeding are not high and you do not have side effects. If you do not fall into this group, your provider will have to weigh risks and benefits carefully.
- If you are already taking aspirin, you should regularly review with your doctor whether your risks for bleeding have changed, since these increase as you get older.
Manson also points out that there are several common misconceptions. For instance, some people wrongly think that taking a high dose of aspirin is better than a low dose of aspirin; or that coated aspirin will protect your stomach. In almost all cases, low dose aspirin is as effective as high dose aspirin for preventing heart attacks, strokes and cancer, and with fewer side effects. In addition, there is little evidence that coated aspirin will prevent stomach bleeds.
Regardless of new data, patients may be reluctant to quit taking their aspirin-a-day. It is difficult to change habits that people think are keeping them healthy. Stoneking, the Cambridge internist, was able to get her patient to reduce her dose from 325 mg to 81 mg. As for getting her to stop completely? "That's going to be a longer conversation," she said.
Dr. Elissa Poorman is a third-year medical resident at Cambridge Health Alliance and plans to practice primary care. She’s on Twitter at @drpoorman.
Correction: An earlier version of this story incorrectly stated the publication date of Dr. Chan's paper: it was 2016, not 2015. We regret the error.
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