Preliminary evaluation of two new rapid immunoturbidimetric D-dimer assaysin patients with clinically suspected venous thromboembolism (VTE)

The practical utility and diagnostic accuracy of two new rapid, automated a nd quantitative immunoturbidimetric D-dimer methods have been evaluated in a population of 123 randomly selected patients with suspected VTE. The STA Liatest D-dimer and MDA D-dimer methods are based on the photo-optical meas urement of the rate of agglutination of antibody-coated latex particles. Th e VIDAS D-dimer automated Elisa was used as the reference method. Diagnosis was confirmed in 51 patients (29 PE, 19 DVT, 3 DVT+PE). The immunoturbidim etric methods compared favorably with the VIDAS Elisa as judged from the co rrelation coefficients of linear regression lines (r = 0.82, MDA vs VIDAS; r = 0.75, STA vs VIDAS) and areas under the curve of ROC plots (VIDAS 0.83; STA 0.83; MDA 0.81). At a discriminant value of 500 ng/mL, all three D-dim er assays showed high sensitivity (96-98%), high NPV (93-97%) and moderate specificity (39-42%). Reproducibility of results around the cut-off is an i mportant aspect of the diagnostic utility of D-dimer assays. CV's of duplic ate determinations in this critical zone showed average values of 5.4% and 17.0% for MDA and STA, respectively. These data demonstrate that such rapid and automated latex-based methods for the quantitative measurement of D-di mer hold promise as reliable and cost-efficient approaches for the exclusio n of VTE. Prospective patient management studies will be required to confir m this.