Harvard Health Letters

Q. My doctor recently advised me to start taking an 81-mg aspirin once a day. I'm a physically active 62-year-old and have been a vegetarian -- mostly vegan -- for 35 years. My BMI is less than 24, my HDL is over 70, and my Framingham risk score is 8 percent. My only problems are systolic blood pressure in the 130s and an occasional episode of arrhythmia. I'd really rather not take aspirin. Am I being foolish in questioning my doctor's advice?

A. It's not foolish to question your doctor's advice. You need to understand the reasoning and the facts behind a doctor's advice, particularly when you wonder if the advice really applies to you. In this case, you think it doesn't -- and judging by the information you've provided, I'm inclined to agree with you.

Aspirin makes platelets in the blood less "sticky," so they're less likely to bunch up into the artery-clogging clots that form when an atherosclerotic plaque ruptures and its contents spill into the bloodstream. There's very good evidence now from many studies that regular use of aspirin can lower the risk of having a heart attack in people who have known atherosclerosis in the coronary arteries, the blood vessels that supply the heart. Regular aspirin use can also lower the risk of stroke in people with atherosclerosis in the arteries that supply the brain. The 81-mg dose your doctor recommended is the standard one for cardiovascular protection.

You don't say anything about any known atherosclerosis, and for several reasons, your risk for heart disease and stroke is probably low. You're relatively young; you exercise regularly; your body mass index (BMI) is excellent (the healthy BMI range is 18.5 to 24.9). Your "good" HDL cholesterol is also where it should be and then some -- any level of 60 mg/dL or above is considered protective against heart disease.

Some readers may not be familiar with the Framingham risk score you mention. It's a widely used formula that estimates the chances of having a heart attack in the next 10 years based on age, gender, and risk factors like HDL levels. Your Framingham score would be even lower if your systolic blood pressure (the first of the two numbers in a blood pressure reading) were lower, but 8 percent is still comfortably in the low range.

The icing on the cake of your low-risk profile is your mainly vegan diet, which is almost certainly low in the substances that promote atherosclerosis: saturated fat, trans fat, and cholesterol.

Even in people like you with stellar health habits and risk factor scores, regular use of aspirin probably can further improve the already good odds against your having a heart attack or stroke. But low-dose aspirin increases the risk of bleeding, particularly in the gut, but also in the brain. Serious bleeding in the gut can be life-threatening if it isn't treated promptly, and bleeding in the brain can cause permanent brain damage and death. And if you have any condition that increases your risk of bleeding in the brain, gut, or elsewhere, the risk from taking aspirin -- even at low, cardioprotective doses -- would be even higher. So aspirin is like most treatments: You need to balance the potential risks against the potential benefits.

If you had a moderate-to-high risk of heart disease -- a Framingham risk score of, say, greater than 10 percent -- most authorities would advise you to take low-dose aspirin. At that level of risk, the benefit from reducing your chance of having a heart attack is, on average, greater than the risk from bleeding. However, because your risk is less than 10 percent, I think your instincts are probably right and you don't need to take regular low-dose aspirin.

Of course, my opinion is based on a very few select things you've told me about your health. You should consult with your doctor before making a decision. He or she knows a lot more about you than I do. -- Anthony L. Komaroff, M.D., Editor in Chief, Harvard Health Letter

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