Aspirin in Primary Prevention of CVD: Rational Use

JoAnn E. Manson, MD, DrPH


May 04, 2022

This transcript has been edited for clarity.

Hello. This is Dr JoAnn Manson, professor of medicine at Harvard Medical School and Brigham and Women's Hospital. I'd like to talk with you about the new guidelines on aspirin in primary prevention of cardiovascular disease, released by the US Preventive Services Task Force (USPSTF) and published in JAMA.

My colleagues Samia Mora, Chrisandra Shufelt, and I were invited to write an editorial on these guidelines for JAMA Internal Medicine. I'd like to review with you the changes in the guidelines and also our perspective on ways to integrate these new recommendations with some of the other guidelines. I want to emphasize that these are primary prevention guidelines, and they do not reflect on the strong recommendation for aspirin use in the secondary prevention setting in the absence of major contraindications. Also, the dose of aspirin being recommended here is generally low: 81 mg daily, or 75 -100 mg daily.

So, what do the 2022 USPSTF guidelines recommend? They are saying that you should not use aspirin in men and women above the age of 60. For those age groups, a D recommendation was given to avoid aspirin use. For ages 40-59, a C recommendation was given for individualized decision-making on aspirin use for select men and women who have a 10-year CVD risk score of at least 10% and do not have an increased risk for bleeding.

How is this different from the 2016 recommendations? There are differences in the age ranges as well as the strengths of recommendations. In 2016, the recommendation was for ages 50-69 and a 10-year CVD risk score of 10% or higher to consider aspirin use with a B recommendation, but the data were insufficient for those below the age of 50 and those aged 70 and older.

What's different in the evidence base between the 2016 and the 2022 guidelines? The evidence for aspirin having at least modest benefits in primary prevention remains quite stable. There are now 13 major clinical trials in primary prevention with more than 160,000 participants. The trials continue to show about a 10% reduction in major CVD events, 11% significant reduction in total MI, 9% reduction in total stroke, and 18% reduction in ischemic stroke, but also substantial increase in the risk for bleeding — about a 58% increased risk for GI bleeding, 31% increase in intracranial bleeding, and overall 44% increase in risk for major bleeding.

Even though the evidence base is quite similar over time in terms of the reduction in CVD events for primary prevention and the increased risk for bleeding, there is an increased appreciation that bleeding risk substantially increases with age; in fact, the bleeding risk about doubles for each decade after age 60. Also, there's less enthusiasm now for the use of aspirin for prevention of colorectal cancer and other cancers. So those are two important changes that may have led to these differences.

When you look carefully at the evidence base presented, there actually is an indication there for continuing to consider aspirin in those aged 60-69 if they have high CVD risk. If you look at the results for quality-adjusted life-years and life-years gained, there is a signal that there is benefit for both men and women, especially those between the ages of 60 and 69, if they have a 10-year CVD risk score of 20% or higher. In patients at higher risk, there still seems to be an overall benefit or neutral results for net life-years gain and benefits for quality-adjusted life-years gained.

This may be particularly important for women because very few women would be eligible for aspirin if the age range is only through age 59, and very few of them are going to have a 10-year risk above 10%. Also, the Women's Health Study aspirin trial has suggested that the greatest benefits were in women above the age of 65. So the evidence base does support some use with a very high risk score (20% or higher for those aged 60 and older).

In our editorial, we recommend considering aspirin for those aged 40-59, similar to what the Task Force recommends — ages 40-59 with a 10-year CVD risk score of 10% or higher — but considering aspirin for those aged 60-69 with a 20% or higher CVD risk score. For those with diabetes, because of that very high risk, especially among women, consider the use of aspirin between the ages of 40 and 69 if the risk is 10% or higher.

How do you balance the risk for bleeding and the benefits in terms of CVD reduction? It's very difficult without the use of a decision support tool. A no-cost, noncommercial clinical decision support tool called Aspirin Guide is available online and in iOS for iPhones. The app has an internal calculator for the CVD risk score as well as a bleeding risk score and will provide number needed to treat vs number needed to harm so that you can compare the two and make an informed decision about the use of aspirin in primary prevention in shared decision-making with the patient.

Thank you so much for your attention. This is JoAnn Manson.

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