Experts recommend a personalized approach when considering daily aspirin for heart disease prevention.

While daily aspirin use is generally recommended in patients with existing heart disease, it’s still unclear if the benefits outweigh the risks in otherwise healthy patients, based on a study published in the Journal of the American Medical Association.

This study, which analyzed data from 13 clinical trials, looked at the role of aspirin use for the prevention of heart disease. This is a form of primary prevention, which aims to prevent disease before it can even occur. All 13 studies included patients who were free of heart disease but may have been at risk for developing it in the future. The trials randomly assigned participants to daily aspirin or an inactive placebo and together included more than 164,000 patients who were followed for a median of 5 years.

What researchers found was that participants taking daily aspirin had 11% lower risk of heart attack, stroke, and heart-related death compared to those taking the inactive placebo. However, aspirin use also increased risk of major bleeding events—a known complication associated with aspirin—by 43%.

Experts note that these risks and benefits are nothing new. Aspirin helps prevent blood clots, which can reduce risk for heart events like heart attack and stroke. At the same time, aspirin’s anti-clotting benefits increases risk for bleeding, which can result in rare but serious complications.

In most cases, these benefits far outweigh the risks for patients with heart disease. But in the most recent analysis, studies included patients without heart disease who generally had lower risk of heart events. Evidence suggests that the end may not always justify the means in these healthier patients.

The take-home message, according to experts, is the importance of personalized treatment plans for patients at risk for heart disease. Each patient’s risk for heart events depends on a number of factors such as age, family history, and overall health. Therefore, it’s important to take these factors into account, as well as a patient’s risk for bleeding, when considering treatments like aspirin.

For certain patients at increased risk for heart disease, like those with diabetes or a strong family history of heart disease, aspirin may be reasonable to help reduce that risk. At the same time, daily aspirin may not be recommended in patients who face increased risk for bleeding or who have no cardiovascular risk factors, since the risks may outweigh the benefits.

Experts note that considering these types of factors, as well as patient preferences, can help in determining when to use aspirin for the primary prevention of heart disease—America’s number one killer.