Discrepant D-dimer results between Innovance D-Dimer and Vidas D-Dimer Exclusion II assays

Background. The concentration of D-dimer (DD) below the 500 ng/mL FEU cut-off value is one of the criteria for exclusion of venous thromboembolism (VTE). The aim of this study was to evaluate the incidence of increased plasma DD in patients with a low risk of VTE among healthy individuals and in patients who have had VTE episodes in the past. Material & Methods. 130 healthy people and 117 patients presenting due to objectively documented VTE episodes were included in this study. DD concentrations were determined using Innovance D-Dimer assay on the BCS XP analyzer and Vidas D-Dimer Exclusion II assay on the VIDAS analyzer. Results. In the group of healthy subjects and patients after VTE episodes DD higher than 500 ng/mL FEU using Innovance D-Dimer assay were in 9 (6.9%) and 4 (3.4%) cases, respectively. Of these 13 patients, only 3 of the group of healthy individuals were with DD level above cut-off using VIDAS D-Dimer assay. In the group of healthy people subjects with discrepant results of DD were older (p=0.04), than the others. Conclusions. Among apparently healthy people or patients with a history of VTE approximately 3 – 7% tested positive with Innovance D-Dimer, while above 50% of them had DD <500 ng/mL using Vidas D dimer Exclusion II. Our data confirm that elevated plasma DD level without careful clinical analysis should not be the basis for ordering expensive imaging testing, but positive DD should be considered to verify using other tests, when clinical diagnosis makes another cause of a such abnormality possible.