key: cord-0717628-dym7qbzl
authors: Bauer, Philippe R.
title: Prothrombotic State in COVID-19: Myth or Reality?
date: 2021-05-24
journal: Mayo Clin Proc
DOI: 10.1016/j.mayocp.2021.05.015
sha: 3a3d2d93217d2f31807f6f5367e639aa4c9b016b
doc_id: 717628
cord_uid: dym7qbzl

nan

COVID-19 infection is associated with an increased risk of veno-thrombo-embolic (VTE) disease in the micro-circulation, as a consequence of pulmonary vascular endothelialitis, with microthromboses. In the macro-circulation, this occurs as a consequence of systemic inflammation and prothrombotic state, with pulmonary embolism and deep vein thrombosis as well as various types of arterial thrombosis 1 . The incidence of VTE is higher in hospitalized patients and the highest in patients admitted to the Intensive Care Unit (ICU) despite a high utilization rate of thromboprophylaxis. In one meta-analysis, the overall incidence of VTE was 24% in patients admitted to the ICU with a predominance of pulmonary embolism (19%) and 9% in patients admitted to the ward 2 . COVID-19 triggers an inflammatory response with cytokine activation, complement activation, immunosuppression, and activation of the coagulation cascade with predominance of hypercoagulable state that includes increase in D-dimer and fibrin/fibrinogen degradation products 3 . The presence of VTE is by itself a risk factor for worse clinical outcome with increased morbidity and mortality 4 . A high incidence of VTE has been described in the initial reports coming from China, Europe, or New York. The incidence of VTE was higher when routine screening was applied 5 no benefit in term of reducing the need for organ support and potential for harm with higher hemorrhagic complications in ICU patients 6 . There is still no convincing evidence that full anticoagulation prevents the occurrence of VTE upon discharge following initial hospitalization.

In this issue, Chaudhary and colleagues 7 present a retrospective observational study of 3,790 adult patients hospitalized with COVID-19 testing, in 19 medical centers of the Mayo Clinic Enterprise around the country from January to early May 2020. Their goal was to evaluate the incidence of VTE in patients hospitalized for COVID-19 infection during the initial months of the pandemic. They compared the incidence of VTE among 102 patients hospitalized with positive COVID-19 testing to 3,688 patients hospitalized during the same period for reasons other than COVID-19 infection and who tested negative for COVID-19. A majority of COVID-19 positive J o u r n a l P r e -p r o o f patients (57.1%) were in the ICU. They found that 1) the incidence of VTE overall was low and similar in both COVID-19 positive and COVID-19 negative groups (2.9% vs. 4.6%) and 2) neither a positive COVID-19 test nor the presence of VTE was associated with 30-day mortality. The lower-than-previously reported incidence may be surprising at first but has already been reported by others 8 and in prospective registries, with an overall rate of VTE of 3% in studies that included 400 patients or more. Previous higher incidence rate might have been attributed to bias related to smaller sample size in earlier studies. With only 102 patients in the study by in Europe like Lombardy in Italy, most centers never reached capacity, a key feature associated with outcome. Centers who remained at or below capacity may have been also more compliant with the best clinical practices recommended by international societies early by the end of March 2020. A center effect is a key feature linked to outcome 9 . Mayo Clinic has a unique model of care that has been associated with a low mortality rate in COVID-19 infection for about that same initial period 10 . The second reason is about VTE prophylaxis. In their study, only 3% of patients did not receive anticoagulation therapy, while 97% received either thromboprophylaxis or therapeutic anticoagulation for a pre-existing condition. The third

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