Bottle of aspirin

Taking aspirin daily may prevent an initial heart attack or stroke in people with elevated risks, as well as reduce the risk of colorectal cancer, according to new draft recommendations from the U.S. Preventive Services Task Force.

Aspirin is an inexpensive, easy-to-obtain medicine cabinet stalwart that has been used for decades to prevent a second heart attack or stroke, said Elliott Antman, M.D., immediate past president of the American Heart Association, professor of medicine at Harvard Medical School and senior physician in the Cardiovascular Division of the Brigham and Women’s Hospital in Boston.

Using aspirin to prevent a first heart attack or stroke – known as primary prevention – has historically been a topic of debate, he said. But scientific data reviewed by the task force supported the new recommendations.

The group advises daily, low-dose aspirin for people ages 50 to 59 with a 10 percent risk of developing cardiovascular disease in 10 years, no bleeding risks and at least a 10-year life expectancy.

Preventing colorectal cancer occurred when people took aspirin for at least five to 10 years, according to the task force.

The draft recommendation also applies to people age 60 to 69, but evidence of a benefit for this age group was slightly weaker. Outside these age groups, there was not enough evidence to justify aspirin therapy.

Most heart attacks and strokes occur when blood flow to the heart or brain is blocked by a blood clot. Aspirin works by “thinning” the blood and preventing the formation of clots.

Exactly how aspirin lowers the risk of colorectal cancer isn’t fully understood, said Antman, although prior research suggests aspirin’s anti-inflammatory effects may reduce the risk of developing tumors in the colon.

In some people, aspirin can lead to complications, including excessive bleeding or a hemorrhagic stroke caused by a burst blood vessel in the brain. Bleeding in the stomach or gastrointestinal tract can also occur, although upset stomach and heartburn are the most common side effects.

“If you haven’t had a heart attack or stroke yet,” said Antman, “your likelihood from benefiting from aspirin will vary depending on your risk of having that first heart attack or stroke.”

Antman gives the example of a healthy, nonsmoking 18-year-old man with normal weight, cholesterol and blood pressure, who has a low 10-year risk of cardiovascular disease. This man’s risk of stomach irritation or bleeding outweighs lowering his already very low heart attack or stroke risk.

On the other hand, a 65-year-old obese male smoker with diabetes, high cholesterol and high blood pressure has a high 10-year risk of cardiovascular disease. His benefit from daily aspirin outweighs his risk of stomach irritation or bleeding, Antman said.

The AHA issued similar guidance in an Aug. 5 statement. The statement recommended low-dose aspirin for middle-aged people who had a 10-year cardiovascular risk of at least 10 percent who didn’t have a higher risk of bleeding.

In both sets of recommendations, experts used a risk assessment tool developed by the AHA and American College of Cardiology to determine the 10-year risk of cardiovascular disease. Developed in 2013, the tool is now available as a free mobile phone app.

Before starting a daily aspirin regimen, people who’ve been told or suspect they’re at risk for a heart attack or stroke should talk to their physician, said Antman.

“The physician is now armed with recommendations from AHA and the U.S. Preventive Task Force that are very similar in their wording,” he said.

The draft aspirin recommendations are posted for public comment for four weeks. Topic experts review the comments, make necessary revisions, then present the revised version to the full task force for a vote. Final recommendations are submitted for publication in a scientific journal.

The USPSTF is a panel of primary care medical professionals with expertise in prevention and evidence-based medicine.