Marone and Rinaldi1 in their study reported cases of deep venous thrombosis (DVT) in hospitalized patients with 2019 novel coronavirus disease (COVID-19). We appreciate the efforts by the authors to present preliminary data on COVID-19-related DVT in their practicing institution and to discuss the possible underlying mechanisms of DVT.
According to the authors, administration of anticoagulant/therapeutic doses of low-molecular-weight heparin (LMWH) in hospitalized COVID-19 patients, instead of prophylactic doses, is the current practice in their practicing institution. Although some may have concern of increased risk of bleeding, bleeding does not appear to be a major manifestation of COVID-19. A higher than traditional standard prophylactic dose of LMWH as adopted in the authors' institution should be encouraged because there is possibly more risk of venous thromboembolism in hospitalized COVID-19 patients than in their non-COVID-19 counterparts.
Particularly, Middeldorp et al2 reported that about 20% of the included COVID-19 patients had venous thromboembolism despite routine thromboprophylaxis with prophylactic doses of LMWH. A comparison with the largest randomized controlled trial thus far of LMWH for the prevention of venous thromboembolism in acutely ill medical patients (non-COVID-19) that reported a thromboprophylaxis failure rate of only 2.77% indicated that the standard prophylactic dose of LMWH in COVID-19 patients may be inadequate.
A higher than usual rate of thromboprophylaxis failure may be due to an increasingly recognized hypercoagulable state with COVID-19 in which a number of changes in circulating prothrombotic factors have been reported in COVID-19 patients: elevated factor VIII level, elevated fibrinogen level, circulating prothrombotic microparticles, and presence of neutrophil extracellular traps.3 , 4 These prothrombotic changes are not usually detected in acutely ill medical patients without COVID-19, in whom the efficacy of standard prophylactic dosing of LMWH is established.
In addition, it has become increasingly clear that obesity is one of the biggest risk factors for severe COVID-19 disease, and therefore obese patients may constitute a significant proportion of hospitalized COVID-19 patients.5 Because high body weight correlates with low anti-factor Xa levels, an anti-factor Xa-guided individualized dosing approach with LMWH may also be adopted in the obese hospitalized COVID-19 population to further reduce the risk of thromboprophylaxis failure. We look forward to studies reporting outcomes on anti-factor Xa-guided approach for dosing of LMWH among COVID-19 patients.
References
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