title: The bedside investigation of pulmonary embolism diagnosis study: a double-blind randomized controlled trial comparing combinations of 3 bedside tests vs ventilation-perfusion scan for the initial investigation of suspected pulmonary embolism.
abstract: BACKGROUND
  We sought to determine whether using combinations of 3 bedside tests (7-variable clinical model, non-enzyme-linked immunosorbent assay D-dimer test, and alveolar dead-space fraction) to exclude pulmonary embolism (PE) before diagnostic imaging was as safe as a standard strategy of starting with ventilation-perfusion (V/Q) scan.
  
  
  METHODS
  In this double-blind, randomized, controlled equivalency trial, patients were randomized to initial bedside tests or to initial V/Q scan without bedside tests. Patients assigned to the bedside test group had a sham V/Q scan performed if at least 2 of 3 bedside test results were negative; otherwise, they underwent an actual V/Q scan. Further diagnostic management was determined by a blinded physician after V/Q scan. The primary outcome measure was recurrent venous thromboembolic events during 3 months among patients who were not taking anticoagulant agents after the initial investigations were completed.
  
  
  RESULTS
  Four hundred fifty-eight consecutive adults with suspected PE were eligible for the study; 398 of 399 consenting and randomized patients completed the study. The follow-up venous thromboembolic event rate was 2.4% in the bedside test group vs 3.0% in the V/Q scan group (P = .76). Pulmonary embolism was excluded in 34% (67/199) of the bedside test group patients with at least 2 negative results on 3 bedside tests vs 18% (35/199) excluded using only the 7-variable clinical model and the D-dimer test.
  
  
  CONCLUSIONS
  Excluding PE with at least 2 negative results on 3 bedside tests safely eliminates the need for diagnostic imaging in 34% of patients with suspected PE.
authors.affiliation: University of Ottawa, Ottawa Health Research Institute, and Department of Medicine, Ottawa Hospital, Ottawa, Ontario, Canada.
authors.forename: Marc A
authors.initials: MA
authors.lastname: Rodger
authors.forename: Christopher N
authors.initials: CN
authors.lastname: Bredeson
authors.forename: Gwynne
authors.initials: G
authors.lastname: Jones
authors.forename: Pasteur
authors.initials: P
authors.lastname: Rasuli
authors.forename: François
authors.initials: F
authors.lastname: Raymond
authors.forename: Anne Marie
authors.initials: AM
authors.lastname: Clement
authors.forename: Alan
authors.initials: A
authors.lastname: Karovitch
authors.forename: Helene
authors.initials: H
authors.lastname: Brunette
authors.forename: Dimitri
authors.initials: D
authors.lastname: Makropoulos
authors.forename: Mark
authors.initials: M
authors.lastname: Reardon
authors.forename: Ian
authors.initials: I
authors.lastname: Stiell
authors.forename: Rama
authors.initials: R
authors.lastname: Nair
authors.forename: Philip S
authors.initials: PS
authors.lastname: Wells
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000032:analysis; D004311:Double-Blind Method; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005338:Fibrin Fibrinogen Degradation Products / Q000032:analysis*; D006801:Humans; D008297:Male; D008875:Middle Aged; D019095:Point-of-Care Systems; D011237:Predictive Value of Tests; D011336:Probability; D011655:Pulmonary Embolism / Q000175:diagnosis* / Q000188:drug therapy / Q000401:mortality; D012016:Reference Values; D012126:Respiratory Dead Space; D012129:Respiratory Function Tests; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D015996:Survival Rate; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014692:Ventilation-Perfusion Ratio
chemical_list: D015415:Biomarkers; D005338:Fibrin Fibrinogen Degradation Products; C036309:fibrin fragment D