Evaluation of D-dimer concentrations measured with three methods in patients with COVID-19

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).