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Publication Briefs

Study Suggests Early Initiation of Prophylactic Anticoagulation for Veterans Hospitalized with COVID-19 Reduces Mortality

Deaths among individuals with COVID-19 have been partially attributed to venous thromboembolism (deep vein thrombosis) and arterial thromboses (blood clot in the arteries). In response, several expert organizations recommend using prophylactic anticoagulation for patients admitted with COVID-19, who do not have a contraindication to this therapy. This observational study sought to determine whether early initiation of prophylactic anticoagulation compared to no anticoagulation decreased risk of death in patients hospitalized with COVID-19. Using VA data, investigators included all Veterans hospitalized between March 1 and July 31, 2020, who were confirmed to have COVID-19 on or within 14 days prior to hospital admission. Patients with a contraindication to receive prophylactic anticoagulation were excluded. The final cohort included 4,297 Veterans; 3,627 (84%) of whom received prophylactic anticoagulation within 24 hours of hospital admission. The main outcome measure was 30-day mortality. Secondary outcomes included: inpatient mortality, initiating therapeutic anticoagulation (proxy for clinical deterioration including thromboembolic events), and bleeding that required transfusion.


  • After accounting for a large number of demographic and clinical characteristics, mortality at 30 days was 14% among Veterans who received prophylactic anticoagulation and 19% among patients who did not, resulting in a 27% decreased risk for 30-day mortality. This benefit appeared to be greater among patients not transferred to the ICU within 24 hours of admission.
  • Similar associations were found for inpatient mortality and initiation of therapeutic anticoagulation.
  • In a post-hoc safety analysis, the receipt of prophylactic anticoagulation was not associated with an increased risk of bleeding that required a transfusion.


  • Findings provide strong real-world evidence to support guidelines recommending the use of prophylactic anticoagulation as initial therapy for COVID-19 patients upon hospital admission. Results have already been disseminated to clinical leaders to support quality improvement efforts to ensure eligible patients receive recommended prophylactic anticoagulation.


  • This study used rigorous pharmacoepidemiological methodology to correct for any underlying differences between patients who received the treatment and those who did not and findings were robust to sensitivity analyses; however because treatment was not randomized, it remains possible that unknown differences may remain between the two groups that could explain findings.

This study was partly funded by HSR&D. Drs. Rentsch, King Jr., Tate, and Justice are part of HSR&D’s Pain Research, Informatics, Multi-morbidities, and Education (PRIME) Center in West Haven, CT. Dr. Gellad is with HSR&D’s Center for Health Equity, Research and Promotion (CHERP) in Pittsburgh and Philadelphia, PA. Dr. Ho is with HSR&D’s Center of Innovation for Veteran-Centered and Value-Driven Care in Denver, CO. Dr. Heidenreich is with HSR&D’s Center for Innovation to Implementation (Ci2i) in Palo Alto, CA. Dr. Atkins is Director of HSR&D in Washington, DC. And Dr. Freiberg is part of the VA Tennessee Valley Healthcare System

Rentsch C, Beckman J, Tomlinson L, et. al. Early initiation of prophylactic anticoagulation for prevention of coronavirus disease 2019 mortality in patients admitted to hospital in the United States: Cohort study. The British Medical Journal. February 11, 2021;372:n311.

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HSR requires notification by HSR-funded investigators about all articles accepted for publication. These journal articles are reviewed by HSR and publication briefs or summaries are written for a select number of articles that are then forwarded to VHA Central Office leadership to keep them informed about important findings or information. Articles to be summarized are selected by HSR based on timeliness of the findings, interest of leadership, or potential impact on the organization. Publication briefs are written for only a small number of HSR published articles. Visit the HSR citations database for a complete listing of HSR articles and presentations.

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