title: Diagnostic value of D-dimer in patients with suspected pulmonary embolism: results from a multicentre outcome study.
abstract: BACKGROUND
  D-dimer tests are used in various diagnostic strategies to exclude pulmonary embolism (PE). However, their role as an exclusionary first-line test is still uncertain, mainly because accuracy of the test varies according to the assay and the studied population.
  
  
  METHODS
  The aim of this multicentre study was to evaluate the accuracy of D-dimer testing in patients with suspected PE. Diagnosis of PE was based on pre-test clinical probability (PCP) evaluation and both single-detector spiral CT (CT) and lower limbs compression ultrasonography (CUS). Lung scanning and/or pulmonary angiography was mandatory when CT or CUS was inconclusive and when both CT and CUS were normal in a patient with a high PCP. All patients were followed-up for 3 months, looking for VTE recurrence. D-dimers were collected within 24 h of inclusion and stored in each local hematology unit, to be analyzed at the end of all inclusions; physicians in charge of the patient were blinded to D-dimer results.
  
  
  RESULTS
  Three hundred and fifty two patients were included in 4 centres. Prevalence of PE was 38.6%. PCP was low in 82 (23.3%), intermediate in 176 (50%) and high in 94 (26.7%) patients. Sensitivity of D-dimer was 96.3% (95% CI: 93-99) and negative predictive value reached 94.4% (95% CI: 90-99). Five patients with a confirmed PE had a D-dimer level below 500 ng/ml (two patients with a high PCP). Among 258 patients with low or intermediate PCP, 80 (31%) had a negative D-dimer test result; three of them had a false negative result and the number needed to test was 3.3. Among 94 patients with a high PCP, 9 had a negative D-dimer test result; two of them had a false negative result and the number needed to test was 13.5.
  
  
  CONCLUSIONS
  These results confirm that rapid assays used in this study can safely exclude PE in first-line testing only in non-high CP patients.
authors.affiliation: Hôpital Antoine Béclère, Assistance Publique Hôpitaux de Paris, Clamart, France.
authors.forename: Florence
authors.initials: F
authors.lastname: Parent
authors.forename: Sophie
authors.initials: S
authors.lastname: Maître
authors.forename: Guy
authors.initials: G
authors.lastname: Meyer
authors.forename: Chantal
authors.initials: C
authors.lastname: Raherison
authors.forename: Hervé
authors.initials: H
authors.lastname: Mal
authors.forename: Rémi
authors.initials: R
authors.lastname: Lancar
authors.forename: Francis
authors.initials: F
authors.lastname: Couturaud
authors.forename: Dominique
authors.initials: D
authors.lastname: Mottier
authors.forename: Philippe
authors.initials: P
authors.lastname: Girard
authors.forename: Gérald
authors.initials: G
authors.lastname: Simonneau
authors.forename: Christophe
authors.initials: C
authors.lastname: Leroyer
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005338:Fibrin Fibrinogen Degradation Products / Q000032:analysis / Q000378:metabolism*; D006801:Humans; D007841:Latex Fixation Tests; D007866:Leg / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011655:Pulmonary Embolism / Q000097:blood* / Q000175:diagnosis* / Q000000981:diagnostic imaging; D012307:Risk Factors; D012680:Sensitivity and Specificity; D016037:Single-Blind Method; D036542:Tomography, Spiral Computed; D014463:Ultrasonography
chemical_list: D005338:Fibrin Fibrinogen Degradation Products; C036309:fibrin fragment D