title: Point of care D-dimer testing in the emergency department: a bioequivalence study.
abstract: BACKGROUND
  D-dimer is used widely as a diagnostic aid in low- and moderate-risk patients with suspected venous thromboembolism (VTE). While our laboratory utilizes VIDAS D-dimer analyzer (bioMérieux SA, France), our emergency department (ED) recently procured a D-dimer analyzer AQT90 FLEX (Radiometer Medical ApS, Denmark) for point of care testing (POCT) to facilitate patient management. We aimed to determine whether the time taken to receive D-dimer results using the 2 different analyzers differed significantly and to quantify the limits of agreement between the results of the 2 methods measured on the same patient.
  
  
  METHODS
  Adult patients presenting to the ED and requiring diagnostic workup for suspected VTE were included in this prospective observational study. Patients underwent simultaneous D-dimer measurements using the 2 different analyzers.
  
  
  RESULTS
  The paired results from 104 patients were analyzed. The median time for the D-dimer results from triage by VIDAS was 258 min (Inter-quartile range [IQR], 173-360) and by POCT was 146 min (IQR, 55-280.5); the median time difference was 101.5 min (IQR, 82-125.5). On an average, POCT D-dimer values were 15% lower on the same sample (limits of agreement, 34-213%). POCT predicted 83% of VIDAS positive results (sensitivity, 83.3% [95% confidence interval (CI), 70.4-91.3%]; specificity, 100% [95% CI, 93.6-100%]). All patients with positive imaging were identified correctly by both methods.
  
  
  CONCLUSIONS
  POCT delivers D-dimer results in significantly shorter turnaround times than pathology services; however, poor bioequivalence between VIDAS and POCT raises the issue of acceptability for use in the ED.
authors.affiliation: Emergency Department, Westmead Hospital, Sydney, Australia.
authors.forename: Shuhana
authors.initials: S
authors.lastname: Perveen
authors.forename: Danielle
authors.initials: D
authors.lastname: Unwin
authors.forename: Amith Loknath
authors.initials: AL
authors.lastname: Shetty
mesh_terms: D000328:Adult; D000368:Aged; D004636:Emergency Service, Hospital; D005260:Female; D005338:Fibrin Fibrinogen Degradation Products / Q000032:analysis*; D006801:Humans; D008297:Male; D008875:Middle Aged; D019095:Point-of-Care Systems; D011446:Prospective Studies; D011933:Reagent Kits, Diagnostic; D012680:Sensitivity and Specificity; D013997:Time Factors; D014057:Tomography, X-Ray Computed; D054556:Venous Thromboembolism / Q000175:diagnosis* / Q000000981:diagnostic imaging
chemical_list: D005338:Fibrin Fibrinogen Degradation Products; D011933:Reagent Kits, Diagnostic; C036309:fibrin fragment D
keywords: Bioequivalence; D-dimer; Length of stay; Point of care systems; Pulmonary embolism