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Full-Dose Clot Prophylaxis Improves Outcomes in Moderate COVID-19

Therapeutic anticoagulation for thromboembolic prophylaxis improved outcomes and possibly survival in a hospitalized but not critically ill COVID-19 population, according to topline results of three large platform trials released today.

The full-dose strategy proved superior to prophylactic dosing in reducing the proportion of patients who progressed to needing ventilation and other vital organ support across the three adaptive platform trials — the National Heart, Lung, and Blood Institute (NHLBI)-sponsored ACTIV-4 trial, REMAP-CAP, and ATTACC.

“A trend in possible reduction of mortality was also observed and is being further studied,” noted a press release from the NHLBI.

If confirmed, it would be only the second such treatment proven to provide a survival benefit for COVID-19 patients. The steroid dexamethasone cut mortality by 27% in hospitalized COVID-19 patients in the RECOVERY trial.

Therapeutic dosing was safe in this moderately ill COVID-19 population, unlike in the critically ill population for which the trials halted the full-dose strategy after seeing signals of harm.

Anticoagulation practice has typically included at least prophylactic dosing for hospitalized COVID-19 patients, due to the excess clotting risk seen with the coronavirus. However, centers have tried intermediate and full therapeutic doses as well, but with little data and only consensus recommendations to go on.

“This will define a new standard of care for patients with COVID-19 in hospital but not on life support,” tweeted ATTACC principal investigator Ryan Zarychanski, MD, of the University of Manitoba in Winnipeg.

Full results of the three trials will be released later, with a press release from his institution noting that “trial investigators are now working as fast as possible to make the full results of the study available so clinicians can make informed decisions about treating their COVID-19 patients.”

“But based on the very stringent criteria used to stop the trial, I would change my practice. In other words, it is unlikely there would be a reversal of the finding,” argued Mary Cushman, MD, also of the University of Manitoba, in an email to MedPage Today.

The interim results spanned more than 1,300 moderately ill patients in general wards who did not receive organ support such as mechanical ventilation at trial enrollment.

All three trials halted their therapeutic anticoagulation study arms for efficacy based on the interim results, although other treatments continue to be studied across the platforms.