Research Activities, July 2013

More research needed to effectively prevent blood clots in special populations

Comparative Effectiveness Research

A new AHRQ research review finds that there is a lack of high-quality evidence on the comparative effectiveness and safety of techniques to prevent venous thromboembolism (VTE) in special populations, including those hospitalized with trauma, traumatic brain injury, burns, or liver disease; patients on antiplatelet therapy; and obese or underweight patients. 

VTE affects an estimated 900,000 Americans every year, resulting in significant morbidity and mortality. There were few high-quality randomized controlled trails on preventing VTE, while the majority of observational studies had a high risk of bias. However, low strength evidence suggests that inferior vena cava (IVC) filter placement is associated with a lower occurrence of pulmonary embolism (PE) and fatal PE in hospitalized patients with trauma compared to no IVC filter placement.

Low strength evidence also suggests that the drug enoxaparin reduces deep vein thrombosis and unfractionated heparin reduces mortality in patients with traumatic brain injury when compared to patients who do not receive anticoagulation agents. Given that clinical trials typically exclude or do not report on these populations, more high-quality observational research on VTE prevention in special populations is needed that controls for confounding variables, such as provider and practice patterns and disease severity. 

These findings can be found in the research review, Pharmacologic and Mechanical Prophylaxis of Venous Thromboembolism Among Special Populations at

Page last reviewed July 2013
Page originally created July 2013
Internet Citation: More research needed to effectively prevent blood clots in special populations. Content last reviewed July 2013. Agency for Healthcare Research and Quality, Rockville, MD.