A rapid and quantitative D-Dimer assay in whole blood and plasma on the point-of-care PATHFAST analyzer

The objective of this study was to evaluate the accuracy indices of the new rapid and quantitative PATHFAST D-Dimer assay in patients with clinically suspected deep-vein thrombosis (DVT). Eighty two consecutive patients (34% DVT, 66% non-DVT) with suspected DVT of a lower limb were tested with the D-Dimer assay with a PATHFAST analyzer. The diagnostic value of the PATHFAST D-Dimer assay (which is based on the principle of a chemiluminescent enzyme immunoassay) for DVT was evaluated with pre-test clinical probability, compression ultrasonography (CUS). Furthermore, each patient underwent contrast venography and computed tomography, if necessary. The sensitivity and specificity of the D-Dimer assay using 0.570 mug/mL FEU as a clinical cut-off value was found to be 100% and 63.2%, respectively, for the diagnosis of DVT, with a positive predictive value (PPV) and negative predictive value (NPV) of 66.7% and 100%, respectively. The correlation between the results of PATHFAST D-Dimer and VIDAS D-Dimer was acceptable (y=1.134x+0.003, r=0.902). The test reproducibility was good (CV%: from 4.0% to 5.0% for plasma and from 7.1% to 7.5% for whole blood) and the total imprecision was very good (CV%: 3.6-5.7%). Whole blood as well as plasma can be used as samples in this assay (y=1.013x-0.010, r=0.971 for heparinized specimens; y=1.068x+0.003, r=0.989 for citrated specimens). Because of its high sensitivity and NPV PATHFAST D-Dimer assay can be useful for the rapid rule out of DVT in patients admitted with suspected thrombosis.