ORIGINAL ARTICLE

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

D Neale¹, C Tovey², A Vali³, S Davies¹, K Myers¹, M Obiako², V Ramkumar², A Hafiz²

¹ Haematology Department, Prince Charles Hospital, Merthyr Tydfil, Mid Glamorgan, Wales
² Emergency Department, Prince Charles Hospital
³ Radiology Department, Prince Charles Hospital

Correspondence to:
Correspondence to:
Mr C Tovey
Emergency Department, Prince Charles Hospital, Merthyr Tydfil, Mid Glamorgan, Wales CF47 9DT, UK; clive.tovey{at}nglam-tr.wales.nhs.uk

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.

Abbreviations: DVT, deep vein thrombosis; ELISA, enzyme linked immunosorbent assay; NPV, negative predictive value; PPV, positive predictive value

Keywords: D-dimers; deep vein thrombosis

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