The effectiveness of the intermediate and therapeutic doses of enoxaparin in COVID-19 patients: A comparative study of factor Xa inhibition

Background: Management of anticoagulant therapy in COVID-19 patients is a critical role. Low Molecular Weight Heparin (LMWH) thromboprophylaxis is already recommended and anti-Factor Xa (anti-FXa) monitoring has been used to titrate LMWH doses. 
Methods: Through a cross-sectional study, we evaluated anti-FXa activity in patients admitted to ICU, receiving intermediate dose (30, 40, 50mg, subcutaneously (SC), twice daily) or therapeutic dose (1 mg/kg, SC, Q12h) of enoxaparin to find whether the patients of these two groups achieve anti-FXa levels in the accepted thromboprophylaxis range.
Results: The occurrence of DVT was 26% in the therapeutic dose and 17% in the intermediate-dose group. D-dimer values were nearly 3.5-fold higher in those who received a therapeutic-dose of anticoagulants than in those who received intermediate dose thromboprophylaxis. Patients in the therapeutic dose group had significantly higher IL-6 levels (p≤0.001). More than one-third of the patients in the therapeutic dose group (n = 8; 42.18%) and approximately half of the patients in the intermediate-dose group (n = 12; 52.2%) achieved the target range level of anti-FXa. Patients who received therapeutic doses were more likely to have anti-FXa levels above the expected range (47.4 Vs 13% in the intermediate dose group. P<0.05).
Conclusion: Therapeutic dose of enoxaparin in critically ill COVID-19 infected patients didn’t reduce the incidence of thromboembolic events and on the other hand may predispose these patients to increased risk of bleeding by increased anti-FXa activity above the desired level. Administration of intermediate-dose thromboprophylaxis is suggested to achieve anti-FXa levels in the accepted thromboprophylaxis range.
