ANTI-THROMBOTIC THERAPY TO AMELIORATE COMPLICATIONS OF COVID-19 (ATTACC): A randomized, international, multi-centre, adaptive, controlled clinical trial

COVID-19 is associated with an unusually high risk of blood clots. Small studies have suggested that anticoagulant (blood thinning) medications that prevent blood clots from forming or travelling may improve the health and survival of hospitalized patients with COVID-19. The goal of this study is to establish whether anticoagulants called heparins can improve outcomes in patients with COVID-19. This study will compare patients who are treated with higher doses of heparin to those that receive usual clinical care, which typically includes low dose heparin. It will measure whether a patient requires intubation (a breathing tube) and need to be on a ventilator, or dies within 30 days of the treatment. It will also monitor patients for other important outcomes such as bleeding, heart attacks, and blood clots. This trial follows a Bayesian adaptive design. Adaptive designs can make clinical trials more flexible by taking into account early results to modify the course of the trial. This is particularly helpful during the COVID-19 pandemic because the trial will make better use of resources in a short timeframe. The trial also uses a randomization method called response-adaptive randomization which allows more patients to be assigned to the superior treatment as the trial progresses. The trial will enroll up to 3000 patients in Canada, the US, Brazil, and Mexico. Participants will be randomly assigned to the investigational arm will receive higher dose unfractionated heparin or low-molecular-weight heparin for up to 14 days. Participants assigned to the control arm will receive usual clinical care, which may include low dose unfractionated heparin or low-molecular-weight heparin. This trial includes collaborations with two large Canadian research networks, the Canadian Venous Thromboembolism Research Network (CanVECTOR) and the Canadian Critical Care Trials Group (CCCTG), and is being conducted in partnership with another global COVID-19 trial called REMAP-CAP.