Prevalence and Risk Factors of Venous Thromboembolism in Critically Ill Patients with Severe COVID-19 and the Association between the Dose of Anticoagulants and Outcomes

Hasan M. Al-Dorzi, Muhannad Q. Alqirnas, Mohamed M. Hegazy, Abdullah S. Alghamdi, Mohammed T. Alotaibi, Mohammed T. Albogami, Mohammed M. Alhafi, Salem Alwadani, Ashraf Elsharkawi, Yaseen M. Arabi

College of Medicine, King Saud bin Abdulaziz University for Health Sciences, King Abdullah International Medical Research Center, and Intensive Care Department, King Abdulaziz Medical City, Ministry of National Guard Health Affairs, Riyadh, Saudi Arabia

DOI: 10.2478/jccm-2022-0023

Introduction: COVID-19 is characterized by a procoagulant state that increases the risk of venous and arterial thrombosis. The dose of anticoagulants in patients with severe COVID-19 pneumonia without suspected or confirmed thrombosis has been debated.
Aim of the study: We evaluated the prevalence, predictors, and outcomes of venous thromboembolism (VTE) in critically ill COVID-19 patients and assessed the association between the dose of anticoagulants and outcomes.
Materials and methods: This retrospective cohort included patients with COVID-19 who were admitted to the ICU between March and July 2020. Patients with clinically suspected and confirmed VTE were compared to those not diagnosed to have VTE.
Results: The study enrolled 310 consecutive patients with severe COVID-19 pneumonia: age 60.0±15.1 years, 67.1% required mechanical ventilation and 44.7% vasopressors. Most (97.1%) patients received anticoagulants during ICU stay: prophylactic unfractionated heparin (N=106), standard-dose enoxaparin (N=104) and intermediate-dose enoxaparin (N=57). Limb Doppler ultrasound was performed for 49 (15.8%) patients and chest computed tomographic angiography for 62 (20%). VTE was diagnosed in 41 (13.2%) patients; 20 patients had deep vein thrombosis and 23 had acute pulmonary embolism. Patients with VTE had significantly higher D-dimer on ICU admission. On multivariable Cox regression analysis, intermediate-dose enoxaparin versus standard-dose unfractionated heparin or enoxaparin was associated with lower VTE risk (hazard ratio, 0.06; 95% confidence interval, 0.01-0.74) and lower risk of the composite outcome of VTE or hospital mortality (hazard ratio, 0.42; 95% confidence interval, 0.23-0.78; p=0.006). Major bleeding was not different between the intermediate- and prophylactic-dose heparin groups.
Conclusions: In our study, clinically suspected and confirmed VTE was diagnosed in 13.2% of critically ill patients with COVID-19. Intermediate-dose enoxaparin versus standard-dose unfractionated heparin or enoxaparin was associated with decreased risk of VTE or hospital mortality.