Background: Patients infected with coronavirus 2 (SARS-CoV-2) appear to be at increased risk for venous thromboembolism (VTE), especially if they become critically ill with coronavirus disease 2019 (COVID-19). Some centers have reported very high rates of thrombosis despite anticoagulant prophylaxis.

Methods: The electronic health record (EHR) of a New Orleans-based health system was searched for all patients with PCR-confirmed SARS-CoV-2 infection who were either admitted to hospital or treated and discharged from an emergency department between March 1 and May 1, 2020. From this cohort, patients with confirmed VTE (either during or after their hospital encounter) were identified by administrative query of the EHR.

Results: Between March 1, 2020 and May 1, 2020, 6,153 patients with COVID-19 were identified; 2,748 of these patients were admitted, while 3,405 received care exclusively through the emergency department. Data on patient outcomes were determined up until and including May 21, 2020. In total, 637 patients required mechanical ventilation and 206 required renal replacement therapy. Within the hospitalized cohort, the overall mortality rate was 24.5% and VTE occurred in 86 patients (3.1%). In the 637 patients who required mechanical ventilation at some point during their hospital stay, 45 developed VTE (7.2%). After a median follow-up of 14.6 days, VTE had been diagnosed in 3 of the 2,075 admitted who were discharged alive (0.14%).

Conclusions: Among 6,153 patients with COVID-19 who were hospitalized or treated in emergency departments, we did not find evidence of unusually high VTE risk. Pending further evidence from prospective, controlled trials, our findings support a traditional approach to primary VTE prevention in patients with COVID-19.


Crowther:Precision Biologicals: Membership on an entity's Board of Directors or advisory committees; Hemostais Reference Laboratories: Honoraria; Pfizer: Speakers Bureau; CSL Behring: Speakers Bureau; Alnylam: Divested equity in a private or publicly-traded company in the past 24 months; Servier Canada: Membership on an entity's Board of Directors or advisory committees; Diagnostica Stago: Speakers Bureau; Asahi Kasei: Membership on an entity's Board of Directors or advisory committees.

Author notes


Asterisk with author names denotes non-ASH members.