Aspirin is the most commonly prescribed drug in the world for both primary and secondary prevention of cardiovascular events such as heart attacks and strokes. Although generally considered safe, taking aspirin carries some risks, including increased bleeding and kidney failure.. A recently released draft guideline from the United States Preventive Services Task Force recommends against prescribing aspirin to reduce cardiovascular event risk in older adults without cardiovascular disease.

The mechanism of action by which aspirin helps prevent cardiovascular events is via its inhibition of the activity of enzymes involved in the production of thromboxane, a substance made by platelets that causes platelet aggregation – an important stage in the atherogenic process – as well as blood clotting and blood vessel constriction. Due to its anti-aggregation properties, aspirin is commonly referred to as a “blood thinner.”

The task force analyzed data from 13 randomized clinical trials that reported on the benefits of aspirin use for the primary prevention of cardiovascular disease and death. The trials included more than 161,000 participants (age range, 53 to 74 years), with aspirin doses of 100 milligrams or less per day or every other day.

They concluded that aspirin therapy should be based on individual risk. An important tool for use in determining risk is the American College of Cardiology/American Heart Association (ACC/AHA) 10-year cardiovascular disease risk calculator. The validated calculator considers age, cholesterol levels, systolic blood pressure level, blood pressure treatment, diabetes status, and smoking status to determine risk. It is important to note that age and race exert strong influence over the calculator’s output.

The task force recommended that initiation of low-dose aspirin for the primary prevention of cardiovascular events in people who are between the ages of 40 and 59 years and whose 10-year cardiovascular event risk is greater than 10 percent should be on a case-by-case basis. They came to this conclusion because current scientific evidence indicates that the net benefit of aspirin use in this group is limited. The task force recommended against initiation of low-dose aspirin for the primary prevention of cardiovascular disease in people who are 60 years or older. People who are currently taking aspirin or have cardiovascular event risk factors should speak with their physician before changing their medication regimen.

Interestingly, omega-3 fatty acids exert anti-clotting effects similar to those of aspirin. Learn more about the health effects of omega-3 fatty acids in this episode featuring Dr. Bill Harris, available on Apple Podcasts and Spotify.

• Link to draft recommendation statement.