title: Diagnosis of pulmonary embolism by multidetector CT alone or combined with venous ultrasonography of the leg: a randomised non-inferiority trial.
abstract: BACKGROUND
  Multislice CT (MSCT) combined with D-dimer measurement can safely exclude pulmonary embolism in patients with a low or intermediate clinical probability of this disease. We compared this combination with a strategy in which both a negative venous ultrasonography of the leg and MSCT were needed to exclude pulmonary embolism.
  
  
  METHODS
  We included 1819 consecutive outpatients with clinically suspected pulmonary embolism in a multicentre non-inferiority randomised controlled trial comparing two strategies: clinical probability assessment and either D-dimer measurement and MSCT (DD-CT strategy [n=903]) or D-dimer measurement, venous compression ultrasonography of the leg, and MSCT (DD-US-CT strategy [n=916]). Randomisation was by computer-generated blocks with stratification according to centre. Patients with a high clinical probability according to the revised Geneva score and a negative work-up for pulmonary embolism were further investigated in both groups. The primary outcome was the 3-month thromboembolic risk in patients who were left untreated on the basis of the exclusion of pulmonary embolism by diagnostic strategy. Clinicians assessing outcome were blinded to group assignment. Analysis was per protocol. This study is registered with ClinicalTrials.gov, number NCT00117169.
  
  
  RESULTS
  The prevalence of pulmonary embolism was 20.6% in both groups (189 cases in DD-US-CT group and 186 in DD-CT group). We analysed 855 patients in the DD-US-CT group and 838 in the DD-CT group per protocol. The 3-month thromboembolic risk was 0.3% (95% CI 0.1-1.1) in the DD-US-CT group and 0.3% (0.1-1.2) in the DD-CT group (difference 0.0% [-0.9 to 0.8]). In the DD-US-CT group, ultrasonography showed a deep-venous thrombosis in 53 (9% [7-12]) of 574 patients, and thus MSCT was not undertaken.
  
  
  CONCLUSIONS
  The strategy combining D-dimer and MSCT is as safe as the strategy using D-dimer followed by venous compression ultrasonography of the leg and MSCT for exclusion of pulmonary embolism. An ultrasound could be of use in patients with a contraindication to CT.
authors.affiliation: Division of Angiology and Hemostasis, Geneva University Hospital and Faculty of Medicine, Geneva, Switzerland. Marc.Righini@hcuge.ch
authors.forename: Marc
authors.initials: M
authors.lastname: Righini
authors.forename: Grégoire
authors.initials: G
authors.lastname: Le Gal
authors.forename: Drahomir
authors.initials: D
authors.lastname: Aujesky
authors.forename: Pierre-Marie
authors.initials: PM
authors.lastname: Roy
authors.forename: Olivier
authors.initials: O
authors.lastname: Sanchez
authors.forename: Franck
authors.initials: F
authors.lastname: Verschuren
authors.forename: Olivier
authors.initials: O
authors.lastname: Rutschmann
authors.forename: Michel
authors.initials: M
authors.lastname: Nonent
authors.forename: Jacques
authors.initials: J
authors.lastname: Cornuz
authors.forename: Frédéric
authors.initials: F
authors.lastname: Thys
authors.forename: Cédric Petit
authors.initials: CP
authors.lastname: Le Manach
authors.forename: Marie-Pierre
authors.initials: MP
authors.lastname: Revel
authors.forename: Pierre-Alexandre
authors.initials: PA
authors.lastname: Poletti
authors.forename: Guy
authors.initials: G
authors.lastname: Meyer
authors.forename: Dominique
authors.initials: D
authors.lastname: Mottier
authors.forename: Thomas
authors.initials: T
authors.lastname: Perneger
authors.forename: Henri
authors.initials: H
authors.lastname: Bounameaux
authors.forename: Arnaud
authors.initials: A
authors.lastname: Perrier
mesh_terms: D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005338:Fibrin Fibrinogen Degradation Products / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011336:Probability; D011655:Pulmonary Embolism / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000209:etiology; D012307:Risk Factors; D014057:Tomography, X-Ray Computed; D014463:Ultrasonography; D020246:Venous Thrombosis / Q000150:complications
chemical_list: D005338:Fibrin Fibrinogen Degradation Products; C036309:fibrin fragment D