Exclusion of deep venous thrombosis with D-Dimer testing - Comparison of 13 D-Dimer methods in 99 outpatients suspected of deep venous thrombosis using venography as reference standard

In a direct assay comparison we evaluated the diagnostic performance of 10 novel D-Dimer assays for the exclusion of deep venous thrombosis (DVT). In addition, 3 conventional ELISA D-Dimer assays were included as reference te sts. The study was performed in 99 consecutive outpatients referred to the emergency department for clinical suspicion of DVT. Venography was used as reference standard and demonstrated the presence of DVT in 50 patients (6 p atients with isolated distal DVT and 44 patients with proximal DVT). The qu alitative D-Dimer assays Minuter and SimpliRED and the quantitative BC DD s howed overall sensitivities (for proximal and distal DVT) of only 80-83% wi th specificities that ranged from 87 to 94%. Overall sensitivity was 94% fo r the qualitative INSTANT I.A. and 98% for the quantitative Turbiquant at a cut-off level equal to the detection limit. Using different cut-off levels a sensitivity of 100% for proximal DVT and For proximal as well as distal DVT could be obtained for NycoCard, IL DD, Liatest, Tinaquant and VIDAS D-D imer assays with specificities that ranged from 31% (NycoCard) to 71% (VIDA S) for proximal DVT and from 12% (NycoCard) to 47% (IL DD) for overall DVT. At a cut-off level equal to the upper limit of the reference range only Ti naquant and VIDAS showed a sensitivity of 100% for proximal as well as for distal DVT with a specificity of 39% and 41% respectively. The results of this study suggest that the VIDAS and Tinaquant D-Dimer assa ys have the highest sensitivity for the exclusion of DVT in outpatients. In outpatients that have a low or moderate pretest probability for DVT, these tests may be used in management studies where anticoagulation is withheld on the basis of D-Dimer testing alone.