Therapeutic Anticoagulation with Heparin in Critically Ill Patients with Covid-19

The REMAP-CAP Investigators, ACTIV-4a Investigators, ATTACC Investigators, et al.

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Thrombosis and inflammation may contribute to morbidity and mortality among patients with coronavirus disease 2019 (Covid-19). We hypothesized that therapeutic-dose anticoagulation would improve outcomes in critically ill patients with Covid-19.


In an open-label, adaptive, multiplatform, randomized clinical trial, critically ill patients with severe Covid-19 were randomly assigned to a pragmatically defined regimen of either therapeutic-dose anticoagulation with heparin or pharmacologic thromboprophylaxis in accordance with local usual care. The primary outcome was organ support–free days, evaluated on an ordinal scale that combined in-hospital death (assigned a value of −1) and the number of days free of cardiovascular or respiratory organ support up to day 21 among patients who survived to hospital discharge.


The trial was stopped when the prespecified criterion for futility was met for therapeutic-dose anticoagulation. Data on the primary outcome were available for 1098 patients (534 assigned to therapeutic-dose anticoagulation and 564 assigned to usual-care thromboprophylaxis). The median value for organ support–free days was 1 (interquartile range, −1 to 16) among the patients assigned to therapeutic-dose anticoagulation and was 4 (interquartile range, −1 to 16) among the patients assigned to usual-care thromboprophylaxis (adjusted proportional odds ratio, 0.83; 95% credible interval, 0.67 to 1.03; posterior probability of futility [defined as an odds ratio <1.2], 99.9%). The percentage of patients who survived to hospital discharge was similar in the two groups (62.7% and 64.5%, respectively; adjusted odds ratio, 0.84; 95% credible interval, 0.64 to 1.11). Major bleeding occurred in 3.8% of the patients assigned to therapeutic-dose anticoagulation and in 2.3% of those assigned to usual-care pharmacologic thromboprophylaxis.


In critically ill patients with Covid-19, an initial strategy of therapeutic-dose anticoagulation with heparin did not result in a greater probability of survival to hospital discharge or a greater number of days free of cardiovascular or respiratory organ support than did usual-care pharmacologic thromboprophylaxis. (REMAP-CAP, ACTIV-4a, and ATTACC numbers, NCT02735707. opens in new tab, NCT04505774. opens in new tab, NCT04359277. opens in new tab, and NCT04372589. opens in new tab.)

Original languageEnglish
Pages (from-to)777-789
Number of pages13
JournalNew England Journal of Medicine
Issue number9
Early online date4 Aug 2021
Publication statusPublished - 26 Aug 2021

Bibliographical note

Funding Information:
REMAP-CAP was supported by the European Union through FP7-HEALTH-2013-INNOVATION: the Platform for European Preparedness Against (Re-)emerging Epidemics (PREPARE) consortium (grant 602525) and the Horizon 2020 research and innovation program: the Rapid European Covid-19 Emergency Research response (RECOVER) consortium (grant 101003589) and by grants from the Australian National Health and Medical Research Council (APP1101719 and APP1116530), the Health Research Council of New Zealand (16/631), the Canadian Institutes of Health Research (Strategy for Patient-Oriented Research Innovative Clinical Trials Program Grant 158584 and COVID-19 Rapid Research Operating Grant 447335), the U.K. National Institute for Health Research (NIHR) and the NIHR Imperial Biomedical Research Centre, the Health Research Board of Ireland (CTN 2014-012), the UPMC Learning While Doing Program, the Translational Breast Cancer Research Consortium, the French Ministry of Health (PHRC-20-0147), the Minderoo Foundation, Amgen, Eisai, the Global Coalition for Adaptive Research, and the Wellcome Trust Innovations Project (215522). The ATTACC platform was supported by grants from the Canadian Institutes of Health Research, LifeArc, Thistledown Foundation, Research Manitoba, CancerCare Manitoba Foundation, Victoria General Hospital Foundation, Ontario Ministry of Health, and the Peter Munk Cardiac Centre. The ACTIV-4a platform was supported by the National Heart, Lung, and Blood Institute of the National Institutes of Health (NIH) and administered through OTA-20-011 and was supported in part by NIH agreement 1OT2HL156812-01. Dr. Goligher is the recipient of an Early Career Investigator award from the Canadian Institutes of Health Research (grant AR7-162822). Dr. Gordon is funded by an NIHR Research Professorship (RP-2015-06-18). Dr. Turgeon is funded by a Canada Research Chair-Tier 2. Dr. Zarychanski is the recipient of the Lyonel G. Israels Research Chair in Hematology (University of Manitoba).

Publisher Copyright:
Copyright © 2021 Massachusetts Medical Society.


  • anticoagulation
  • heparin
  • low molecular weight heparin
  • Covid-19
  • adaptive platform trial
  • critical care


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