title: Magnitude of D-dimer matters for diagnosing pulmonary embolus.
abstract: OBJECTIVE
  The objective of this study is to determine whether the magnitude of the D-dimer correlates with a higher likelihood of pulmonary embolus (PE).
  
  
  METHODS
  We performed an electronic chart review at our academic, tertiary care center, annual emergency department (ED) census greater than 100000. All patients with a chest computed tomographic (CT) scan with intravenous contrast and an elevated D-dimer level obtained in the ED between January 2001 and July 2008 were identified. Specific, predetermined, predefined data elements including sex, age, D-dimer level, and final ED diagnosis were recorded by a hypothesis-blinded extractor using a preformatted data form. D-dimer level less than 0.58 μg/mL constitutes the normal laboratory reference range for our turbidometric D-dimer assay. Data were analyzed using standard statistical methods, and a linear regression analysis was performed for correlation analysis of D-dimer and diagnosis of PE.
  
  
  RESULTS
  We identified 544 subjects who had both a chest CT scan performed and an elevated D-dimer level obtained in the ED. Fifty-eight subjects (10.7%; mean D-dimer, 4.9 μg/mL) were diagnosed with PE, and 486 (89.3%; mean D-dimer, 2.0) did not have a PE. The percentages of PE diagnoses for D-dimers in the ranges 0.58 to 1.0, 1.0 to 2.0, 2.0 to 5.0, 5.0 to 20.0, and greater than 20.0 (n = 11) were 3.6%, 8.0%, 16.2%, 35.3%, and 45.5%, respectively. The positive predictive value of PE for D-dimer level cutoffs of greater than 0.58, greater than 1.0, greater than 2.0, greater than 5.0, and greater than 20.0 was 10.7%, 14.6%, 22.2%, 37.8%, and 45.5%, respectively. Increasing D-dimer values were strongly correlated with the presence of PE (odds ratio, 1.1685 per stratum; P < .001).
  
  
  CONCLUSIONS
  Increasing magnitude of D-dimer correlates with increasing likelihood of PE diagnosed by CT angiography.
authors.affiliation: Department of Emergency Medicine, Mount Sinai School of Medicine, New York, NY 10029, USA.
authors.forename: Kaushal
authors.initials: K
authors.lastname: Shah
authors.forename: Joshua
authors.initials: J
authors.lastname: Quaas
authors.forename: Daniel
authors.initials: D
authors.lastname: Rolston
authors.forename: Shalu
authors.initials: S
authors.lastname: Bansal
authors.forename: Theodore
authors.initials: T
authors.lastname: Bania
authors.forename: David
authors.initials: D
authors.lastname: Newman
authors.forename: Dan
authors.initials: D
authors.lastname: Wiener
authors.forename: Jarone
authors.initials: J
authors.lastname: Lee
mesh_terms: D005260:Female; D005338:Fibrin Fibrinogen Degradation Products / Q000032:analysis*; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011655:Pulmonary Embolism / Q000097:blood / Q000175:diagnosis* / Q000000981:diagnostic imaging; D012372:ROC Curve; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed
chemical_list: D005338:Fibrin Fibrinogen Degradation Products; C036309:fibrin fragment D