COVID-19 Post-hospital Thrombosis Prevention Study

This study is an adaptive, prospective, randomized platform trial designed to compare the effectiveness and safety of antithrombotic therapy with no antithrombotic therapy after hospitalization for 48 hours or longer for COVID-19. For Stage 1 of this study, participants will be randomized to either prophylactic anticoagulation or no anticoagulant therapy for 30 days, and then followed for an additional 60 days after the completion of treatment (total duration of follow-up, 90 days).
Anticoagulant Agent vs. Placebo

Key Personnel

Thomas Ortel, MD, PhD Study Chair (Duke University)thomas.ortel@duke.edu919-681-6049
Alison Morris, MD, MS Study Co-Chair (University of Pittsburgh Medical Center)morrisa@upmc@edu
Tracy Wang, MD Study PI (Duke University)

Primary Outcome(s)

Thrombotic Event
A binary composite endpoint of venous and arterial thrombotic complications—including new, symptomatic proximal, or distal DVT of the upper or lower extremities, PE, and new thrombosis of other veins (including cerebral sinus and splanchnic veins), ischemic stroke, myocardial infarction, other arterial thromboembolism (e.g., mesenteric or acute limb ischemia), and all-cause mortality.


Adults > 18 years of age with COVID-19 who are hospitalized for 48 hours or longer and who are ready for discharge from the hospital


Anticoagulation: Apixaban 2.5 mg


Planned Enrollment

5,320 in total (2,270 to each treatment arm) for Stage 1

Power and Interim Assessments

In order to ensure an 80% power to detect a CE rate reduction of 35% through anticoagulation use, the study needs to enroll at least 2,530 participants per arm.


At least through Day 90 with visits at Days 2, 10, 20, 30, 45 and 90.