Performances of a new, automated latex assay for the exclusion of venous thromboembolism.

The performance of a new latex-enhanced turbidimetric assay, D-Dimer PLUS, has been evaluated with two analyzers performing various coagulation assays: the BCS Analyzer and the BCT Analyzer. A precision study showed total coefficients of variation ranging from 2.7 to 11.1% with the BCS Analyzer and from 2.5 to 6.6% with the BCT Analyzer. We investigated the ability of D-Dimer PLUS to exclude venous thromboembolism in 312 outpatients suspected of either pulmonary embolism or deep venous thrombosis. Three months follow-up was available for all patients. With the BCS Analyzer, we determined a cut-off value of 190 ng/ml, which gave a sensitivity of 97.9% [95% confidence interval (CI), 92.6-99.7%], a specificity of 37.9% (95% CI, 30.9-43.8%) and a negative predictive value of 97.6% (95% CI, 91.7-99.7%). With the BCT Analyzer, at a cut-off value of 130 ng/ml, sensitivity was 96.8% (95% CI, 91.0-99.3%), specificity was 45.2% (95% CI, 38.5-51.2%) and the negative predictive value was 97% (95% CI, 91.6-99.4). This new assay is fast and fully automated, and its performance is suitable to exclude venous thromboembolism. Management studies should be performed to assess its utility.