title: Usefulness of preemptive anticoagulation in patients with suspected pulmonary embolism: a decision analysis.
abstract: BACKGROUND
  The diagnostic workup of pulmonary embolism (PE) may take several hours. The usefulness of anticoagulant treatment while awaiting the results of diagnostic tests has not been assessed. The objective of this study was to compare the risks and benefits of bid low-molecular-weight heparin vs no treatment in patients with suspected PE.
  
  
  METHODS
  We developed a decision tree with the following outcomes: mortality related to untreated and treated PE, mortality due to major hemorrhage, and intracranial bleeding. The timeframe extended from the suspicion of PE to its confirmation or exclusion. Most probabilities were derived from data from the Computerized Registry of Patients with VTE (RIETE). We estimated the incidence of bleeding by categories of clinical prediction rules of PE from a recent diagnostic management study of PE. Uncertainty was assessed through one-way and probabilistic sensitivity analyses.
  
  
  RESULTS
  The model favored preemptive anticoagulation if the diagnostic delay was > 6.3 h, > 2.3 h, and > 0.3 h (Revised Geneva low, intermediate, and high probability) and > 8.1 h and > 1.7 h (Wells unlikely and likely). With a diagnostic delay of 6 h, the absolute mortality reduction with anticoagulation was 0%, 0.02%, and 0.1% for low, intermediate, and high clinical probability, respectively. In one-way sensitivity analyses, the mortality of untreated PE was the most critical variable. Probabilistic analyses reinforced the superiority of anticoagulation in intermediate- and high-probability patients and suggested that low-probability patients might not benefit from treatment after diagnostic delays of < 6 to 8 h.
  
  
  CONCLUSIONS
  Our model suggests that patients with intermediate and high/likely probabilities of PE benefit from preemptive anticoagulation. With a low probability, the decision to treat may rely on the expected diagnostic delay.
authors.affiliation: Division of General Internal Medicine, Department of Internal Medicine, University Hospitals of Geneva, Geneva, Switzerland. Electronic address: marc.blondon@hcuge.ch.
authors.forename: Marc
authors.initials: M
authors.lastname: Blondon
authors.affiliation: Division of Angiology and Hemostasis, Department of Internal Medicine, University Hospitals of Geneva, Geneva, Switzerland.
authors.forename: Marc
authors.initials: M
authors.lastname: Righini
authors.affiliation: Division of General Internal Medicine, Bern University Hospital, Bern, Switzerland.
authors.forename: Drahomir
authors.initials: D
authors.lastname: Aujesky
authors.affiliation: Department of Internal Medicine and Chest Diseases and EA 3878, Brest University Hospital, Brest, France.
authors.forename: Grégoire
authors.initials: G
authors.lastname: Le Gal
authors.affiliation: Division of General Internal Medicine, Department of Internal Medicine, University Hospitals of Geneva, Geneva, Switzerland.
authors.forename: Arnaud
authors.initials: A
authors.lastname: Perrier
mesh_terms: D000925:Anticoagulants / Q000627:therapeutic use*; D003661:Decision Support Techniques; D003663:Decision Trees; D003955:Diagnostic Tests, Routine; D005260:Female; D006470:Hemorrhage / Q000453:epidemiology / Q000401:mortality; D006495:Heparin, Low-Molecular-Weight / Q000627:therapeutic use; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D011655:Pulmonary Embolism / Q000175:diagnosis* / Q000517:prevention & control*; D012042:Registries; D013997:Time Factors; D061665:Time-to-Treatment
chemical_list: D000925:Anticoagulants; D006495:Heparin, Low-Molecular-Weight