CLINICAL AND LABORATORY CRITERIA FOR THE PERSONALIZATION OF ANTICOAGULANT THERAPY IN PATIENTS WITH SEVERE COVID-19

Abstract

Introduction. Severe COVID-19 is associated with endothelial dysfunction, immunothrombosis, and coagulopathy, which contribute to thrombotic complications and mortality. Despite the widespread use of anticoagulant therapy, the optimal strategy for dose selection and treatment escalation in severe disease remains debated. Aim of study. To assess associations of hemostatic parameters and clinical characteristics with anticoagulant regimens and clinical outcomes in patients with severe COVID-19 and to identify markers that may support individualized treatment decisions. Materials and Methods. A retrospective cohort study included 268 patients with severe COVID-19 treated at Bila Tserkva City Hospital No. 1 in 2021. Patients were divided into three groups according to the anticoagulant regimen: prophylactic-dose low-molecular-weight heparin (LMWH) (n=65), therapeutic-dose LMWH (n=118), and escalation therapy with subsequent transition to unfractionated heparin (n=85). Hemostatic parameters including D-dimer, platelet count, prothrombin index (PTI), international normalized ratio (INR), prothrombin time (PT), and activated partial thromboplastin time (aPTT) were analyzed. Clinical outcomes included hospital mortality, length of hospital stay, and intensive care unit (ICU) stay. Results. Hospital mortality was highest in the prophylactic-dose group (90.8%), compared with 61.9% in the therapeuticdose group and 41.2% in the escalation group (p<0.001). The most pronounced between-group and longitudinal changes were observed for D-dimer, platelet count, and aPTT. Elevated D-dimer was associated with more severe disease and the use of more intensive anticoagulant regimens. Platelet-count changes may reflect progression of coagulation abnormalities, whereas aPTT dynamics were relevant to monitoring unfractionated heparin therapy. Owing to the retrospective design, these findings indicate associations rather than causal effects. Conclusion. Individualization of anticoagulant therapy in severe COVID-19 should rely on comprehensive clinical assessment and dynamic monitoring of hemostatic parameters within current guidelines. D-dimer, platelet count, and aPTT may contribute to this assessment; however, none should be used alone to determine anticoagulant-dose escalation.