title: Do emergency physicians use serum D-dimer effectively to determine the need for CT when evaluating patients for pulmonary embolism? Review of 5,344 consecutive patients.
abstract: OBJECTIVE
  The purpose of our study was to investigate whether D-dimer screening is being used effectively to determine the need for MDCT in diagnosing acute pulmonary embolism (PE) in emergency department patients.
  
  
  METHODS
  We performed a retrospective review of all patients who underwent D-dimer testing or MDCT in the emergency department from January 1, 2003, through October 31, 2005. A D-dimer value of > 0.43 microg/mL was considered positive. Diagnosis of PE was made on the basis of the MDCT. Clinical algorithms for diagnosing PE mandate that patients with a low clinical suspicion for PE undergo D-dimer testing, then MDCT if positive. For patients with a high clinical suspicion for PE, MDCT should be performed without D-dimer testing.
  
  
  RESULTS
  Of 3,716 D-dimer tests, 1,431 (39%) were positive and 2,285 (61%) were negative. MDCT was performed in 166 (7%) patients with negative D-dimer results and in 826 (58%) patients with positive D-dimer results. The prevalence of PE in patients with a high clinical suspicion and no D-dimer testing was 9% (139/1,628), which was higher than the rate of PE in the positive D-dimer group at 2% (19/826) (p < 0.0001). There was no significant difference in the prevalence of PE in the positive and negative D-dimer groups (2% vs 0.6%, respectively) (p = 0.23). The sensitivity and negative predictive value of D-dimer for PE were 95% (95% CI, 73.1-99.7%) and 99% (95% CI, 96.2-99.9%), respectively.
  
  
  CONCLUSIONS
  D-dimer screening is not used according to established diagnostic algorithms to determine the need for MDCT in diagnosing acute pulmonary embolism in our emergency department.
authors.affiliation: Department of Diagnostic Imaging, Warren Alpert Medical School of Brown University and Rhode Island Hospital, 593 Eddy Street, Providence, RI 02903, USA.
authors.forename: Michael T
authors.initials: MT
authors.lastname: Corwin
authors.forename: Jay H
authors.initials: JH
authors.lastname: Donohoo
authors.forename: Robert
authors.initials: R
authors.lastname: Partridge
authors.forename: Thomas K
authors.initials: TK
authors.lastname: Egglin
authors.forename: William W
authors.initials: WW
authors.lastname: Mayo-Smith
mesh_terms: D000465:Algorithms; D015415:Biomarkers / Q000097:blood; D004636:Emergency Service, Hospital; D005260:Female; D005338:Fibrin Fibrinogen Degradation Products; D006801:Humans; D008297:Male; D011237:Predictive Value of Tests; D015995:Prevalence; D011655:Pulmonary Embolism / Q000097:blood* / Q000000981:diagnostic imaging* / Q000453:epidemiology; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed
chemical_list: D015415:Biomarkers; D005338:Fibrin Fibrinogen Degradation Products; C036309:fibrin fragment D