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

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

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Thrombosis and inflammation may contribute to the risk of death and complications among patients with coronavirus disease 2019 (Covid-19). We hypothesized that therapeutic-dose anticoagulation may improve outcomes in noncritically ill patients who are hospitalized with Covid-19.

In this open-label, adaptive, multiplatform, controlled trial, we randomly assigned patients who were hospitalized with Covid-19 and who were not critically ill (which was defined as an absence of critical care–level organ support at enrollment) to receive pragmatically defined regimens of either therapeutic-dose anticoagulation with heparin or usual-care pharmacologic thromboprophylaxis. 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. This outcome was evaluated with the use of a Bayesian statistical model for all patients and according to the baseline d-dimer level.

The trial was stopped when prespecified criteria for the superiority of therapeutic-dose anticoagulation were met. Among 2219 patients in the final analysis, the probability that therapeutic-dose anticoagulation increased organ support–free days as compared with usual-care thromboprophylaxis was 98.6% (adjusted odds ratio, 1.27; 95% credible interval, 1.03 to 1.58). The adjusted absolute between-group difference in survival until hospital discharge without organ support favoring therapeutic-dose anticoagulation was 4.0 percentage points (95% credible interval, 0.5 to 7.2). The final probability of the superiority of therapeutic-dose anticoagulation over usual-care thromboprophylaxis was 97.3% in the high d-dimer cohort, 92.9% in the low d-dimer cohort, and 97.3% in the unknown d-dimer cohort. Major bleeding occurred in 1.9% of the patients receiving therapeutic-dose anticoagulation and in 0.9% of those receiving thromboprophylaxis.

In noncritically ill patients with Covid-19, an initial strategy of therapeutic-dose anticoagulation with heparin increased the probability of survival to hospital discharge with reduced use of cardiovascular or respiratory organ support as compared with usual-care thromboprophylaxis. (ATTACC, ACTIV-4a, and REMAP-CAP numbers, NCT04372589. opens in new tab, NCT04505774. opens in new tab, NCT02735707. opens in new tab, and NCT04359277. opens in new tab.)
Original languageEnglish
Pages (from-to)790-802
Number of pages13
JournalNew England Journal of Medicine
Issue number9
Early online date4 Aug 2021
Publication statusPublished - 26 Aug 2021

Bibliographical note

Funding Information:
The ATTACC platform was supported by grants from the Canadian Institutes of Health Research, LifeArc Foundation, Thistledown Foundation, Research Manitoba, Ontario Ministry of Health, Peter Munk Cardiac Centre, CancerCare Manitoba Foundation, and Victoria General Hospital Foundation. The ACTIV-4a platform was sponsored by the National Heart, Lung, and Blood Institute, National Institutes of Health (NIH) (grant numbers, OTA-20-011 and 1OT2HL156812-01). The pilot program (PROTECT) was funded in part by a grant (UL1TR001445) from the New York University Clinical and Translational Science Award program, supported by the National Center for Advancing Translational Sciences of the NIH. The REMAP-CAP platform was supported by the European Union through FP7-HEALTH-2013-INNOVATION: the Platform for European Preparedness Against (Re-)emerging Epidemics (PREPARE) consortium (602525) and the Horizon 2020 research and innovation program: the Rapid European Covid-19 Emergency Research response (RECOVER) consortium (101003589); by 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 Learning While Doing Program at the University of Pittsburgh Medical Center, the Breast Cancer Research Foundation, the French Ministry of Health (PHRC-20-0147), the Minderoo Foundation, Am-gen, Eisai, the Global Coalition for Adaptive Research, and the Wellcome Trust Innovations Project (215522). Dr. Goligher is the recipient of an Early Career Investigator award from the Canadian Institutes of Health Research (grant AR7-162822). Dr. Gordon is supported by an NIHR Research Professorship (RP-2015-06-18), Dr. Shankar-Hari by an NIHR Clinician Scientist Fellowship (CS-2016-16-011), and Dr. Turgeon by a Canada Research Chair (Tier 2). Dr. Zarychanski is the recipient of the Lyonel G. Israels Research Chair in Hematology (University of Manitoba).

Funding Information:
* Listed are data that were included in the analysis involving patients with moderate severity of coronavirus disease 2019 (Covid-19). The denominators of patients in the anticoagulation group and the thrombophylaxis group are un-equal owing to response-adaptive randomization. The baseline characteristics of the patients according to d-dimer level are provided in Table S2 in the Supplementary Appendix. To convert the values for creatinine to micromoles per liter, multiply by 88.4. ULN denotes upper limit of the normal range. † Race or ethnic group was reported by the patients. ‡ The body-mass index is the weight in kilograms divided by the square of the height in meters. § Severe cardiovascular disease was defined as a baseline history of heart failure, myocardial infarction, coronary artery disease, peripheral arterial disease, or cerebrovascular disease (stroke or transient ischemic attack) in the ATTACC (Antithrombotic Therapy to Ameliorate Complications of Covid-19) and ACTIV-4a (A Multicenter, Adaptive, Ran-domized Controlled Platform Trial of the Safety and Efficacy of Antithrombotic Strategies in Hospitalized Adults with COVID-19) platforms and as a baseline history of New York Heart Association class IV symptoms in the REMAP-CAP platform (Randomized, Embedded, Multifactorial Adaptive Platform Trial for Community-Acquired Pneumonia). ¶ Chronic respiratory disease was defined as a baseline history of asthma, chronic obstructive pulmonary disease, bron-chiectasis, interstitial lung disease, primary lung cancer, pulmonary hypertension, active tuberculosis, or the receipt of home oxygen therapy. ‖ Not listed are 74 patients who were coenrolled in the REMAP-CAP Antiplatelet Domain (39 in the anticoagulation group and 35 in the thromboprophylaxis group). ** In REMAP-CAP, levels of oxygen support (including no support) below the level of high-flow nasal cannula were not reported. †† The relative proportion of patients who were randomly assigned in each platform was imbalanced owing to imple-mentation of response-adaptive randomization in ATTACC on December 15, 2020. ‡‡ A total of 215 patients who were enrolled in the ATTACC platform were funded by the ACTIV4a platform by the National Heart, Lung, and Blood Institute. §§ Other participating countries were Mexico, Nepal, Australia, the Netherlands, and Spain.

Publisher Copyright:
Copyright © 2021 Massachusetts Medical Society.


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


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