ABSTRACT
Introduction: Severe COVID-19 has been associated with aberrant coagulation factor activities, particularly in patients with a thrombotic event (TE). Management of anticoagulant is critical in the care of hospitalized patients with COVID-19.Hypothesis: Evaluation of a point-of-care (POC), functional, clot-time-based coagulation test to detect the anticoagulant effect of therapeutic unfractionated heparin (UFH) in hospitalized SARS-CoV-2-positive patients who developed a TE. Methods: An IRB-approved analysis of 36 citrated plasma specimens from 26 SARS-CoV-2-positive patients and 10 matched negative controls was performed. A Clotting Time Score (CTS), a measure of factor-specific inhibition (i.e. anticoagulant activity), was derived for each patient. CTS results were compared with traditional coagulation tests. Five UFH COVID-19 samples with low CTS scores (<10) were spiked with uniform dosing of UFH, low molecular weight heparin (LMWH), apixaban, or argatroban and retested to assess anticoagulation response. Results: The CTS detected subtherapeutic UFH anticoagulation levels more frequently in COVID-19 cases compared with controls (76% vs. 17%). Prothrombin Times, activated Partial Thromboplastin Times, anti-Xa levels, and antithrombin activity did not correlate with each other or with the CTS in the COVID-19 samples. CTS correlated with both FV and Factor X activity (R =0.49, Spearman R=-0.68), which form the prothrombinase complex. The CTS was 94% sensitive and 67% specific for the occurrence of TEs in patients on UFH. CTS demonstrated a consistent anticoagulant response only to argatroban (100%) compared with other anticoagulants (60%). Conclusions: The CTS, generated using a novel, low-volume, rapid POC coagulation test is a strong indicator of the therapeutic effect of UFH anticoagulation in COVID-19 patients and may provide a predictive measure of TEs potentially occurring from anticoagulation resistance.