Project Summary

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

Design Element Description
Design Randomized controlled trial
Population Adults ages 18 and older who have heart disease, are at high risk of having a heart attack or stroke, do not have a history of GI bleed or aspirin allergy, and are not taking certain other medicines to prevent heart attack and stroke; female patients must not be pregnant or nursing
  • Low-dose aspirin (81 mg)
  • High-dose aspirin (325 mg)

Primary: composite of death, hospitalization for heart attack, or hospitalization for stroke

Secondary: coronary revascularization procedures, hospitalization for serious bleeding, quality of life, other patient-reported outcomes

Timeframe Timeframe Length of follow-up for collecting data on primary outcomes. View Glossary 30-month follow-up for primary outcomes

More to Explore...

Results of this Study Presented at ACC.21, Published in NEJM

People with cardiovascular disease who took aspirin to lower their chances of having a heart attack or stroke experienced similar health benefits, including reduced death and hospitalization, whether they took a high or low dose of the medication, according to findings from this study released in May 2021.


Summary of Results
English | Español (pdf)
(Credit: DCRI)

The results were presented at ACC.21, the American College of Cardiology’s 70th Annual Scientific Session, and simultaneously published in the New England Journal of Medicine.

This study is the largest aspirin dosing trial conducted in routine care and clinical settings, and the first randomized controlled trial conducted using PCORnet®, the National Patient-Centered Clinical Research Network. Learn more here and through the Summary of Results (right).


Which Aspirin Dose Is Best to Protect Patients with Heart Disease? Our First PCORnet Study
In this blog post, former PCORI Executive Director Joe Selby, MD, MPH, discusses the Board of Governors' approval of funding for this study and some of the key aspects of its design and goals.

Study Website

ADAPTABLE: The Aspirin Study
Duke Clinical Research Institute


ADAPTABLE Study Different by Design
Study co-investigator Adrian F. Hernandez, MD, MHS, FAHA, discusses how this study is uniquely designed in comparison with more traditional trials, and how it aims to achieve its goals in an efficient, effective and patient-centered manner.

Journal Citations

Related Journal Citations

Project Information

William Schuyler Jones, MD*
Duke University
Aspirin Dosing: A Patient-Centric Trial Assessing Benefits and Long-term Effectiveness (ADAPTABLE)

Key Dates

May 2015
December 2022

Study Registration Information

*Matthew Roe, MD, MHS was the original Principal Investigator on the project.


Has Results
Health Conditions Health Conditions These are the broad terms we use to categorize our funded research studies; specific diseases or conditions are included within the appropriate larger category. Note: not all of our funded projects focus on a single disease or condition; some touch on multiple diseases or conditions, research methods, or broader health system interventions. Such projects won’t be listed by a primary disease/condition and so won’t appear if you use this filter tool to find them. View Glossary
Populations Populations PCORI is interested in research that seeks to better understand how different clinical and health system options work for different people. These populations are frequently studied in our portfolio or identified as being of interest by our stakeholders. View Glossary
Intervention Strategy Intervention Strategies PCORI funds comparative clinical effectiveness research (CER) studies that compare two or more options or approaches to health care, or that compare different ways of delivering or receiving care. View Glossary
State State The state where the project originates, or where the primary institution or organization is located. View Glossary
Last updated: January 20, 2023