Evaluation of the Simplify d-dimer assay as a screening test for the diagnosis of deep vein thrombosis in an emergency department

Objectives: To evaluate the use in an emergency department of a new d-dimer assay (Simplify d-dimer) as a screening test for deep vein thrombosis (DVT). Methods: 187 outpatients with clinical features suspicious of acute DVT were entered into this study. A Simplify d-dimer test was performed in the emergency department on all patients. A SimpliRED d-dimer test and a semi-automated latex agglutination assay (Auto-d-dimer 700 on a Thromboscreen 400C analyser) were performed in the haematology laboratory. All patients were investigated with contrast venography to confirm or exclude the diagnosis of DVT. Results: The Simplify test had a sensitivity of 94.1% and a negative predictive value (NPV) of 94.8%. These results compared favourably with the SimpliRED test (sensitivity 74.5%, NPV 89.7%) and the latex agglutination assay (sensitivity 90.2%, NPV 92.2%). This increased sensitivity was at the cost of a lower specificity, the specificity of the three d-dimer tests being Simplify 40.4%, SimpliRED 83.1%, and latex agglutination 43.4%. Conclusions: Simplify proved to be a rapid and easy to use test and may be useful for use in the emergency department as part of a diagnostic algorithm for deep vein thrombosis. Further larger scale studies are needed.