title: Diagnostic accuracy and user-friendliness of 5 point-of-care D-dimer tests for the exclusion of deep vein thrombosis.
abstract: BACKGROUND
  Point-of-care D-dimer tests have recently been introduced to enable rapid exclusion of deep venous thrombosis (DVT) without the need to refer a patient for conventional laboratory-based D-dimer testing. Before implementation in practice, however, the diagnostic accuracy of each test should be validated.
  
  
  METHODS
  We analyzed data of 577 prospectively identified consecutive primary care patients suspected to have DVT, who underwent 5 point-of-care D-dimer tests-4 quantitative (Vidas®, Pathfast™, Cardiac®, and Triage®) and 1 qualitative (Clearview Simplify®)-and ultrasonography as the reference method. We evaluated the tests for the accuracy of their measurements and submitted a questionnaire to 20 users to assess the user-friendliness of each test.
  
  
  RESULTS
  All D-dimer tests showed negative predictive values higher than 98%. Sensitivity was high for all point-of-care tests, with a range of 0.91 (Clearview Simplify) to 0.99 (Vidas). Specificity varied between 0.39 (Pathfast) and 0.64 (Clearview Simplify). The quantitative point-of-care tests showed similar and high discriminative power for DVT, according to calculated areas under the ROC curves (range 0.88-0.89). The quantitative Vidas and Pathfast devices showed limited user-friendliness for primary care, owing to a laborious calibration process and long analyzer warm-up time compared to the Cardiac and Triage. For the qualitative Clearview Simplify assay, no analyzer or calibration was needed, but interpretation of a test result was sometimes difficult because of poor color contrast.
  
  
  CONCLUSIONS
  Point-of-care D-dimer assays show good and similar diagnostic accuracy. The quantitative Cardiac and Triage and the qualitative Clearview Simplify D-dimer seem most user-friendly for excluding DVT in the doctor's office.
authors.affiliation: University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Geert-Jan
authors.initials: GJ
authors.lastname: Geersing
authors.forename: Diane B
authors.initials: DB
authors.lastname: Toll
authors.forename: Kristel J M
authors.initials: KJ
authors.lastname: Janssen
authors.forename: Ruud
authors.initials: R
authors.lastname: Oudega
authors.forename: Marloes J C
authors.initials: MJ
authors.lastname: Blikman
authors.forename: René
authors.initials: R
authors.lastname: Wijland
authors.forename: Karen M K
authors.initials: KM
authors.lastname: de Vooght
authors.forename: Arno W
authors.initials: AW
authors.lastname: Hoes
authors.forename: Karel G M
authors.initials: KG
authors.lastname: Moons
mesh_terms: D005260:Female; D005338:Fibrin Fibrinogen Degradation Products / Q000032:analysis*; D006801:Humans; D008297:Male; D008875:Middle Aged; D019095:Point-of-Care Systems; D011446:Prospective Studies; D020246:Venous Thrombosis / Q000097:blood / Q000175:diagnosis*
chemical_list: D005338:Fibrin Fibrinogen Degradation Products; C036309:fibrin fragment D