title: Comparison of high specificity with standard versions of a quantitative latex D-dimer test in the assessment of community pulmonary embolism: HaemosIL D-dimer HS and pulmonary embolism.
abstract: BACKGROUND
  D-dimer assays are sensitive but have poor specificity. False positive results lead to extra imaging and hospital admissions.
  
  
  OBJECTIVE
  To make a pilot comparison of the diagnostic accuracy of the standard quantitative latex HemosIL D-dimer assay with a newer HemosIL D-dimer HS version designed to have improved specificity. PATIENTS / METHODS: Consecutive patients presenting from the community to an Emergency Department that were investigated for suspected pulmonary embolism using a D-dimer test were included in the study. Standard and D-dimer HS tests were performed. Pulmonary Embolism was diagnosed on the basis of imaging studies or post-mortem at any time from presentation to 90 days thereafter.
  
  
  RESULTS
  The prevalence of Pulmonary Embolism was 4.5% (18/402). The sensitivity, specificity, negative predictive value, and positive predictive value for the standard quantitative D-dimer test was 100% (81.5 - 100.0), 49.2% (44.1 - 54.3),100% (98.1 - 100.0), and 8.5% (5.1 - 13.0), respectively, and 100% (81.5 - 100.0), 58.3% (53.2 - 63.3),100% (98.4 - 100.0), and 10.1% (6.1 - 15.5), for the D-dimer HS test. There were 35 (16%) fewer 'false positives' using the D-dimer HS assay compared with the standard assay.
  
  
  CONCLUSIONS
  D-dimer HS has superior specificity to the standard quantitative D-dimer test without any loss of sensitivity. The generation of fewer false positive results should lead to less unnecessary diagnostic imaging; the use of which is associated with increased hospital admissions and length of stay. The HS assay may therefore have significant health economic benefits.
authors.affiliation: Department of Emergency Medicine, Christchurch Hospital, Christchurch, New Zealand. martin.than@cdhb.govt.nz
authors.forename: Martin P
authors.initials: MP
authors.lastname: Than
authors.forename: Jennifer
authors.initials: J
authors.lastname: Helm
authors.forename: Kristi
authors.initials: K
authors.lastname: Calder
authors.forename: Michael W
authors.initials: MW
authors.lastname: Ardagh
authors.forename: Mark
authors.initials: M
authors.lastname: Smith
authors.forename: Dylan F
authors.initials: DF
authors.lastname: Flaws
authors.forename: Lutz
authors.initials: L
authors.lastname: Beckert
mesh_terms: D004636:Emergency Service, Hospital; D005189:False Positive Reactions; D005260:Female; D005338:Fibrin Fibrinogen Degradation Products / Q000592:standards*; D005500:Follow-Up Studies; D006801:Humans; D007407:Interviews as Topic; D008297:Male; D008875:Middle Aged; D009520:New Zealand / Q000453:epidemiology; D010865:Pilot Projects; D011237:Predictive Value of Tests; D015995:Prevalence; D011446:Prospective Studies; D011651:Pulmonary Artery / Q000000981:diagnostic imaging; D011655:Pulmonary Embolism / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000453:epidemiology; D011859:Radiography; D012015:Reference Standards; D012680:Sensitivity and Specificity; D013997:Time Factors
chemical_list: D005338:Fibrin Fibrinogen Degradation Products; C036309:fibrin fragment D