Increasing dosages of low-molecular-weight heparin in hospitalized patients with Covid-19.

We conducted an observational cohort study in adult patients consecutively admitted for the respiratory illness Covid-19 to our hub hospital from March 9 to April 7, 2020. The high observed rate of venous thromboembolism prompted us to increase the prophylactic doses of enoxaparin from 40 mg daily up to 1 mg/kg twice daily in patients admitted to intensive care units (ICU), 0.7 mg/kg twice daily in high-intensity of care wards and 1 mg/kg daily in low-intensity of care wards. Patients on high enoxaparin doses were compared to those who received prophylaxis with the standard dosage. Efficacy endpoints were mortality, clinical deterioration, and the occurrence of venous thromboembolism, safety endpoint was the occurrence of major bleeding. Of 278 patients with Covid-19, 127 received prophylaxis with high enoxaparin doses and 151 with standard dosage. At 21 days, the incidence rate of death and clinical deterioration were lower in patients on higher doses than in those on the standard dosage (hazard ratio 0.39, 95% confidence interval 0.23-0.62), and the incidence of venous thromboembolism was also lower (hazard ratio 0.52, 95% confidence interval 0.26-1.05). Major bleeding occurred in four of 127 patients (3.1%) on the high enoxaparin dosage. In conclusion, in the cohort of patients with Covid-19 treated with high enoxaparin dosages we observed a 60% reduction of mortality and clinical deterioration and a 50% reduction of venous thromboembolism compared to standard dosage prophylaxis. However, 3% of patients on high enoxaparin dosages had non-fatal major bleeding.

The ADAMTS13-von Willebrand factor axis in COVID-19 patients.

BACKGROUND: Severe coronavirus disease 2019 (COVID-19) is characterized by an increased risk of thromboembolic events, with evidence of microthrombosis in the lungs of deceased patients. OBJECTIVES: To investigate the mechanism of microthrombosis in COVID-19 progression. PATIENTS/METHODS: We assessed von Willebrand factor (VWF) antigen (VWF:Ag), VWF ristocetin-cofactor (VWF:RCo), VWF multimers, VWF propeptide (VWFpp), and ADAMTS13 activity in a cross-sectional study of 50 patients stratified according to their admission to three different intensity of care units: low (requiring high-flow nasal cannula oxygenation, n = 14), intermediate (requiring continuous positive airway pressure devices, n = 17), and high (requiring mechanical ventilation, n = 19). RESULTS: Median VWF:Ag, VWF:RCo, and VWFpp levels were markedly elevated in COVID-19 patients and increased with intensity of care, with VWF:Ag being 268, 386, and 476 IU/dL; VWF:RCo 216, 334, and 388 IU/dL; and VWFpp 156, 172, and 192 IU/dL in patients at low, intermediate, and high intensity of care, respectively. Conversely, the high-to-low molecular-weight VWF multimers ratios progressively decreased with increasing intensity of care, as well as median ADAMTS13 activity levels, which ranged from 82 IU/dL for patients at low intensity of care to 62 and 55 IU/dL for those at intermediate and high intensity of care. CONCLUSIONS: We found a significant alteration of the VWF-ADAMTS13 axis in COVID-19 patients, with an elevated VWF:Ag to ADAMTS13 activity ratio that was strongly associated with disease severity. Such an imbalance enhances the hypercoagulable state of COVID-19 patients and their risk of microthrombosis.