PB0049 - Thromboprophylaxis with enoxaparin for symptomatic COVID-19 managed in the ambulatory setting: Pooled analysis of the OVID and ETHIC trials

Sunday, June 25, 2023

18:30 – 19:30 ET

Room: Exhibition

Presenting Author(s)

Stefano Barco, MD, PhD, FESC (he/him/his)

MD, PhD
Department of Angiology, University Hospital of Zurich
Zurich, Zurich, Switzerland

Co-Author(s)

SV

Saverio Virdone

PhD
Thrombosis Research Institute
London, England, United Kingdom
FC

Frank Cools

Prof.
Department of Cardiology, General Hospital Klina
Brasschaat, Belgium, Antwerpen, Belgium
RF

Riccardo Fumagalli

MD
Department of Angiology, University Hospital Zurich
Zurich, Zurich, Switzerland
AG

Andrea Götschi

MsC
Department of Biostatistics at Epidemiology, Biostatistics and Prevention Institute, University of Zurich
Zurich, Zurich, Switzerland
GK

Gloria Kayani

PhD
Thrombosis Research Institute
London, England, United Kingdom
NK

Nils Kucher

Prof.
Department of Angiology, University Hospital Zurich
Zurich, Zurich, Switzerland
KP

Karen S. Pieper

PhD
Thrombosis Research Institute
London, England, United Kingdom
DV

Davide Voci

MD
Department of Angiology, University Hospital Zurich
Zurich, Zurich, Switzerland
UH

Ulrike Held

Professor
Department of Biostatistics at Epidemiology, Biostatistics and Prevention Institute, University of Zurich,
Zurich, Zurich, Switzerland
Ajay K. K. Kakkar, KBE PC

Director
Thrombosis Research Institute, London, UK
London, England, United Kingdom

Background: The addition of antithrombotic treatment may improve the disease course in non-critically ill, symptomatic COVID-19 patients treated in ambulatory setting.

Aims: We did an individual patient-level analysis of two randomized trials identified from a systematic review of the literature, the OVID and ETHIC studies, which compared thromboprophylaxis with enoxaparin for either 14 (OVID) or 21 days (ETHIC) vs. standard of care (no thromboprophylaxis).

Methods: We included symptomatic outpatients with newly diagnosed COVID-19 who were at least 50 years old or had at least one additional risk factor. The primary outcome was adapted from that of the individual trials and included unplanned hospitalisation and all-cause death within 30 days from randomization. Secondary outcomes include major cardiovascular venous and arterial thromboembolic events within 30 (+/-3) days from randomization. The same outcomes were also assessed over 90-day follow-up. The primary safety outcome was major bleeding (ISTH criteria).

Results: The primary outcome occurred in 6.0% of patients in the enoxaparin group (n=339) vs. 5.8% of controls (n=352) for a risk ratio (RR) of 1.05 (95%CI 0.57-1.92). The overall 30-day cumulative incidence of cardiovascular events was 0.9% vs. 1.8%, respectively (RR 0.52; 95%CI 0.13-2.06). The majority of cardiovascular events were represented by venous thromboembolic events, occurring in 0.6% vs. 1.5% of patients, respectively. A similar distribution of outcomes between the treatment groups was observed for all outcomes over 90 days; Figure 1. No major bleeding events occurred in the enoxaparin group vs. one (0.3%) in the control group.

Conclusion(s): This individual patient-level analysis of randomized trials suggests no clinical benefit of early administration of enoxaparin thromboprophylaxis in outpatients with COVID-19. Since both studies were terminated prematurely for futility, the combined study may also have reduced power for conclusive statements.