ABSTRACT
Background: COVID-19 is associated with an increased risk of venous thrombosis, even when patients are on standard-dose antithrombotic prophylaxis. Hence, the identification of biomarkers of thrombosis helps tailoring dosage of antithrombotic prophylaxis. D-dimer has been extensively employed as a biomarker and cut-off values at hospital admission have been proposed to stratify the risk of thrombosis and make decision on prophylaxis. However, D-dimer measurement is not standardized, and it is unknown if the cut-off values used for decision making can be used interchangeably between methods. Aim(s): To assess for concordance of results obtained with different commercially available laboratory methods measuring D-dimer. Method(s): Plasma samples collected from COVID-19 patients at the Hospital of Cremona were evaluated for D-dimer with three widely used immunoturbidimetric methods (Liatest D-di, Stago, Asnieres, France;D-dimer HS 500, Werfen, Orangeburg, NY;Innovance D-dimer, Siemens, Marburg, Germany). Result(s): A total of 87 COVID-19 patients [54 male and 33 female, median age of 73 years (range 28-98)] were enrolled in the study. No significant differences were found between mean D-dimer concentrations obtained with the three methods even when stratifying D-dimer levels in 4 groups (<1000, 1000-2000, 2000-5000, >5000 ng/mL) (Figure 1). The three methods showed substantial result agreement [Stago-vs- Werfen and Siemens-vs- Stago (Cohen's kappa coefficient of 0.760 and 0.699, respectively)] to an almost perfect agreement [Siemens-vs- Werfen (Cohen's kappa coefficient of 0.811)], with a p-value < 0.001. Results from the three methods showed a good linear correlation (Rho = 0.94) (Figure 2). Conclusion(s): The relatively good concordance of D-dimer results among the three investigated methods indicates that D-dimer cut-off values could be used interchangeably regardless of the method used for testing. The results pave the way to clinical trials aimed to assess the value of D-dimer as a biomarker to make decision on the intensity of antithrombotic prophylaxis in COVID-19 patients. (Figure Presented).
ABSTRACT
Background : Covid-19 infection is associated with a widespread global activation of coagulation and affected patients are at an increased risk of thrombosis. Aims : Heparin therapy is effective in various setting in preventing thromboembolic complications and aim of this study was to assess heparin response in COVID-19 patients through anti-FXa test. Methods : In 52 patients, M:F ratio 59:41, median age 59 years old, admitted in different intensity of care units of our hospital, treated with different regimens of heparin (100 U/kg every 24 h in low intensity care, 70 U/kg every 12 h in intermediate intensity care and 100 U/kg every 12 h in intensive care unit), anti-FXa levels were measured immediately before and 3 h after subcutaneous enoxaparin administration. On the same samples thrombin generation tests were performed. Results : Patients treated with 100 U/kg every 24 h and 70 U/ kg every 12 h had median anti-FXa basal levels in the prophylactic range, respectively 0.18 and 0.22 U/ml, while patients treated with 100 U/kg every 12 h were in the anticoagulant range (0.37 U/ ml). Despite heparin therapy thrombin generation was elevated in COVID-19 patients, indicating a high level of coagulation activation. Conclusions : In conclusion we demonstrated that the biological response to enoxaparin in COVID-19 patients is in the expected range using anti-FXa assay and patients are not resistant to heparin therapy.