13 March 2023

A study looking at treating hospitalised COVID-19 patients with an increased dose of anticoagulation therapy has had mixed results – but effective strategies are emerging, according to the researchers.

Previous trials of anticoagulation therapy for these patients reported conflicting results. So a research team set out to accurately determine the safety and effectiveness of this approach for patients hospitalised due to COVID but not in intensive care. The team was led jointly by Drs Valentin Fuster and Gregg Stone of the Mount Sinai Hospital in New York City, USA.

3,398 participants recruited in ten countries from August 2020 to September 2022 were given either a ‘prophylactic’ (lower) dose of the anticoagulant enoxaparin, a ‘therapeutic’ (higher) dose of enoxaparin, or a ‘therapeutic’ dose of the anticoagulant apixaban.

The primary endpoint of the trial was a 30-day composite of all-cause mortality, requirement for ICU level-of-care, systemic thromboembolism, or ischemic stroke. This primary outcome occurred in 11% of patients receiving a therapeutic dose, and 13% of those receiving a prophylactic dose, but the difference was not statistically significant.

However, all-cause mortality was 7% in the prophylactic dose group and 5% in the therapeutic dose group – a statistically significant relative reduction of 30%. Intubation rates between the groups was also significantly different – 8.4% in the prophylactic dose group, and 6.4% in the therapeutic dose group.

Full details appeared in the Journal of the American College of Cardiology last week.

The researchers write: “Fewer patients who were treated with therapeutic-dose anticoagulation required intubation or died.”

Dr Fuster said: “Although our study did not reach its primary endpoint, it has shown that patients admitted to the hospital for COVID-19 who are not yet critically ill but who have early signs of lung damage caused by the virus substantially benefit from a higher dose of blood-thinning medication to stop disease progression, prevent the need for lung intubation and prevent death, without a significant increase in the risk of bleeding.”


Stone GW, Farkouh ME, Lala A, Tinuoye E, Dressler O, Moreno PR, Palacios IF, Goodman SG, Esper RB, Abizaid A, Varade D, Betancur JF, Ricalde A, Payro G, Castellano JM, Hung IF, Nadkarni GN, Giustino G, Godoy LC, Feinman J, Camaj A, Bienstock SW, Furtado RHM, Granada C, Bustamante J, Peyra C, Contreras J, Owen R, Bhatt DL, Pocock SJ, Fuster V, for the FREEDOM COVID Anticoagulation Strategy Randomized Trial Investigators. (2023) “Anticoagulation Strategies in Non-Critically Ill Patients Hospitalized with COVID-19: A Randomized Clinical Trial.” Journal of the American College of Cardiology, doi: 10.1016/j.jacc.2023.02.041.

Link: https://www.sciencedirect.com/science/article/pii/S0735109723045278

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