This research project is in progress. PCORI will post the research findings on this page within 90 days after the results are final. In the meantime, results have been published in peer-reviewed journals, as listed below.

What is the research about?

Heart disease is the most common killer in the United States. Every 40 seconds, someone in the United States has a heart attack. Many patients who survive develop complications such as heart failure or stroke.

Doctors often suggest that patients take aspirin to prevent future heart attacks or strokes. But aspirin can cause bleeding within the body or an allergic reaction. Currently, doctors don’t know whether low-dose or high-dose aspirin is better at protecting against a heart attack or stroke while also keeping the risk of bleeding as low as possible. Patients and their doctors also want to know whether patient characteristics such as age, gender, ethnicity or race play a role in which dose of aspirin will be safest and most effective. This study compares patients with heart disease who take low-dose aspirin with patients who take high-dose aspirin. The research team is studying whether one dose is less likely to cause bleeding and is more effective at preventing heart attacks, strokes, or deaths.

Who can this research help?

Findings from this study can help patients with heart disease and their doctors determine which aspirin dose is safer and more effective to treat heart disease in the long term.

What is the research team doing?

The research team is enrolling up to 15,000 patients who have heart disease and are at high risk of having a heart attack or stroke. Researchers are assigning patients by chance to take either a low-dose (81 mg) or high-dose (325 mg) aspirin each day. The team follows patients for up to four years to track death, hospitalization for heart attack or stroke, and evidence of heart disease. The team is comparing the benefits and side effects of each aspirin dose for all patients and for patients of different genders, ages, ethnicities, and races. Researchers also want to study how well each dose worked in patients who have other health problems in addition to heart disease, such as diabetes.

The research team uses information from electronic health records that doctors already collect during patients’ usual medical visits. The research team has also created a patient web portal to collect information directly from patients.

Study leaders include researchers, patients, doctors, and other healthcare providers. The research team also works with a group of patient representatives to make decisions about the study procedures, create study materials, and share results.

Research methods at a glance