Antithrombotic Therapy to Ameliorate Complications of COVID-19 (ATTACC)

Study Summary

Endothelial injury as a consequence of SARS-CoV-2 infection leads to a dysregulated host inflammatory response and activation of coagulation pathways. Macro- and micro-vascular thrombosis may contribute to morbidity, organ failure, and death. Therapeutic anticoagulation with heparin may improve clinical outcomes in patients with COVID-19 through anti-thrombotic, anti-inflammatory, and anti-viral activities of heparins. This pragmatic, Bayesian adaptive randomized controlled trial will determine whether therapeutic anticoagulation with heparin (subcutaneous low molecular weight heparin or intravenous unfractionated heparin) versus usual care reduces the need for intubation or death in hospitalized patients with COVID-19. The trial uses an adaptive design which was chosen to overcome limitations in available data to inform a priori estimation of event rates and possible effect sizes. The adaptive design also includes response-adaptive randomization based on baseline D-dimer level, probing for differential efficacy across subgroups defined based on initial D-dimer level. This Bayesian adaptive randomized trial will stop at a conclusion 1) when the posterior probability that the proportional odds ratio is greater than 1.0 reaches 99% (definition of benefit); 2) when the posterior probability that the proportional odds ratio is greater than 1.2 is less than 10% (definition of futility) or; 3) when the posterior probability that the proportional odds ratio is less than 1.0 is greater than 90% (definition of harm). The trial will enroll a maximum of 3,000 patients, although in many simulations the trial may require fewer patients. The trial is strategically aligned with the international REMAP-CAP/COVID platform trial to accelerate evidence generation.

Primary Outcome

The primary endpoint in the trial is days alive and free of organ support at day 21. This endpoint is defined as the number of days that a patient is alive and free of organ support through the first 21 days after trial entry. Organ support is defined as receipt of invasive or non-invasive mechanical ventilation, high flow nasal oxygen (\>30 L/min), vasopressor therapy, or ECMO support. Death at any time (including beyond 21 days) during the index hospital stay is assigned the worst possible sco

Interventions

• DRUG Heparin