Project Summary

PCORI has identified the need for large studies that look at real-life questions faced by diverse patients, caregivers, and clinicians. To address this need, PCORI launched the Pragmatic Clinical Studies initiative in 2014. Pragmatic clinical studies allow for larger-scale studies with longer timelines to compare the benefits and harms of two or more approaches known to be effective for preventing, diagnosing, treating, or managing a disease or symptom. They focus on everyday care for a wide range of patients. This research project is one of the studies PCORI awarded as part of this program.

This research project is in progress. PCORI will post the research findings on this page within 90 days after the results are final.

What is the research about?

Each year, 6 million fractures are treated in the United States, and 2.3 million patients are admitted to hospitals after sustaining a serious fracture. People who fracture certain bones, such as the hip or thighbone, have a high risk of getting blood clots. Blood clots restrict how blood moves throughout the body.  They can be fatal if they travel to the lungs, brain, or other organs. Guidelines recommend that doctors give patients blood-thinning medicine to prevent blood clots from forming after treatment for certain fractures or other serious injuries. The most common blood-thinning medicines in emergency rooms are called low-molecular-weight heparins. Aspirin is another common medicine that prevents blood clots. We don’t know which of these medicines works better in fracture patients. These medicines can cause problems, such as internal bleeding and complications during surgery.

This study is comparing whether low-molecular-weight heparins or aspirin work better for preventing blood clots after serious fractures.

 Who can this research help?

This research can help patients at risk for blood clots after fractures. The research can also help doctors and other clinicians choose the best medicine for preventing blood clots in patients who have a high risk of blood clots and who have fractures that need surgery.

What is the research team doing?

The study includes 18 trauma hospitals across the United States and Canada. Patients who are admitted at one of the hospitals with a serious bone fracture and who agree to participate in the study receive blood-thinning medicine or aspirin. Researchers assign patients to the types of medicine by chance. The research team is monitoring patients for three months after their fractures to see which group has fewer deaths because of a blood clot in their lungs and fewer complications such as blood clots in their legs, internal bleeding, or infections. In addition, the research team is comparing the two groups’ satisfaction and out-of-pocket costs.

The research team works with people who have had hip or thighbone fractures, people who have survived blood clots, caregivers, hospital staff, and medical experts. The research team surveyed patients who had serious injuries and designed the study in response to their concerns.

Research methods at a glance

Design Element Description
Study Design Randomized controlled trial
Population Adults getting care in trauma centers for serious bone fractures
  • Low-molecular-weight heparins
  • Aspirin

Primary: number of deaths because of a blood clot in the lungs, number and type of blood clots developed, surgical complications

Secondary: patient satisfaction, patient out-of-pocket costs

Timeframe 3-month follow-up for primary outcomes

Project Information

Robert O'Toole, MD, TRD
University of Maryland Baltimore
A Randomized Pragmatic Trial Comparing the Complications and Safety of Blood Clot Prevention Medicines Used in Orthopedic Trauma Patients

Key Dates

July 2016
May 2023

Study Registration Information


Award Type
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: March 4, 2022