COVID-19 Positive Outpatient Thrombosis Prevention in Adults Aged 40-80

Platform trial comparing the effectiveness of anticoagulation agents against antiplatelet agents and a placebo control arm. Stage 1 study agents include anticoagulation with apixaban (1 arm for 2.5 mg dosage and 1 arm for 5 mg dosage), with low dose aspirin as the antiplatelet.
Anticoagulant Agent VS. Antiplatelet Agent VS. Placebo

Key Personnel

Jean M. Connors, MD PI (Brigham and Women’s Hospital) 732-5190
Paul M. Ridker, MD Trial Chair (Brigham and Women’s Hospital) 732-8790

Primary Outcome(s)

Thrombotic Event
A composite endpoint of need for hospitalization for cardiovascular/pulmonary events, symptomatic deep venous thrombosis, pulmonary embolism, arterial thromboembolism, myocardial infarction, ischemic stroke, and all-cause mortality for up to 45 days after initiation of assigned treatment.


Adults age between 40 and 80 years, COVID-19 positive, who do not require hospitalization.


  1. Anticoagulation: apixaban 2.5 mg
  2. Anticoagulation: apixaban 5 mg
  3. Antiplatelet agent: low dose aspirin
  4. Placebo

Planned Enrollment

7,000 in total (1,750 to each treatment arm) for Stage 1

Power and Interim Assessments

80% power to detect a 30% relative reduced risk

90% power to detect a 34% relative reduced risk

For stage 1, considering apixaban 5.0mg superiority with 8.0% placebo rate.


Minimum of weekly follow-up through Day 75.