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Aspirin for prevention: Should you take it?

In this final piece on aspirin for prevention of heart attack and stroke, Randall Stafford explains factors for doctors and patients to consider.

Editor's note: In March 2019, new guidelines were released that recommend more limited use of aspirin for prevention of cardiovascular disease. This is the final installment of a revised blog series.

Fred is now ready to visit the doctor. Fred, as you may recall is 58 and slightly overweight. His friend suggested that he should start taking low-dose aspirin to help prevent heart attack and stroke, but Fred isn't sure, so he schedules a visit with his doctor.

To prepare, Fred has his blood tested to get information such as his total cholesterol level, and uses an online risk calculator, like this one from the American College of Cardiology, to calculate his risk of experiencing a heart attack or stroke in the next 10 years. Using that calculator, Fred's risk is 20 percent.

At the office visit, Fred's doctor reviews new studies that show us the risks of side effects may outweigh or balance the potential benefits (such as prevention of a cardiovascular disease event such as heart attack or stroke).

However, since Fred's risk score is 20% he is at high risk for a future event. Fred mentions that his dad suffered from a stroke and it is really important for Fred to try and prevent this from happening to him. Fred is less concerned about the potential side effects such as bleeding since he is at average risk for abnormal bleeding.

Based on these preferences, Fred and his doctor decide that aspirin is appropriate, and Fred agrees to take 81 mg of aspirin each evening. They discuss other strategies to prevent heart attacks and opt to increase Fred's lisinopril dose to lower his blood pressure. They also strategize about how Fred can quit smoking as well as lose a few pounds. Later at the pharmacy, Fred picks up his new lisinopril prescription and buys a $4 bottle of 300 low-dose aspirin tablets.

Let's take a closer look at the issues that Fred discussed with his doctor.

They include:

Bleeding: If a person has a higher than average chance of bleeding (especially past bleeding), then aspirin should probably not be used unless they are at a very high risk of a heart attack or stroke.

Colon cancer: Having a higher than normal chance of developing colon cancer might prompt use of aspirin even in someone at moderate risk of heart disease and stroke.

Aspirin dose: Low dose (81 mg) is just as effective for heart disease and stroke prevention as higher doses, which carry a greater chance of internal bleeding.  

Age: Current guidelines focus on ages 50-69 years, but many health specialists believe it can be beneficial for some people in their 70s to start taking aspirin.

Continuing aspirin: Fred and his doctor focused on the decision to start aspirin, but once started in a high-risk individual, aspirin should be continued indefinitely, except when major bleeding problems occur.  If aspirin was started earlier in someone at low risk, it is reasonable to consider stopping aspirin after a discussion with a clinician. 

Other wellness strategies: If you are at a high enough risk of heart attack or stroke to take aspirin, you can lower your risk of those events by treating your blood pressure and cholesterol more aggressively. In fact, these other interventions are likely to be more effective than starting aspirin. In addition, adopting healthier behaviors related to physical activity, food, sleep, and stress can further reduce your risk of heart attack, stroke and cancer.

Past research tells us that many people who may benefit from aspirin are not taking this low-cost, potentially helpful drug. On the other hand, some people who are less likely to benefit have started aspirin in the past, putting themselves at unnecessary risk of stomach and brain bleeding.

Knowing your risk for heart attack or stroke is important for many forms of prevention. Men older than 50 and women over 60 should find out their risk factors. This means having blood pressure measured and lab tests done for cholesterol. Once you have the needed information, use an online calculator to estimate your risk.

Aspirin should be used when there is a compelling combination of high risk of future stroke or heart attack, low risk of bleeding problems, and a preference for tolerating bleeding for the sake of preventing heart attacks and strokes.

The decision to start aspirin for prevention requires a discussion between you and your health care provider to review the potential risks, benefits, and your personal preferences. Talking to your health provider is critical because there are many factors that need to be considered when making this decision, and your calculated risk may have implications for other disease prevention strategies.

Please take the time to find out if aspirin is right for you or not.

This is the final piece in a revised series of blog posts on aspirin for prevention. The first covered the potential benefits and harms of aspirin, while the second post covered how to calculate the risk of a future serious heart or stroke and how to interpret this risk information.

Randall Stafford, MD, PhD, a professor of medicine and director of the Program on Prevention Outcomes and Practices, is a primary care internal medicine physician at Stanford. He is developing practical strategies to improve how physicians and consumers approach chronic disease treatment and prevention. Additional information about the preventive use of aspirin is available at

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