title: Validation of a clinical prognostic model to identify low-risk patients with pulmonary embolism.
abstract: OBJECTIVE
  To validate the Pulmonary Embolism Severity Index (PESI), a clinical prognostic model which identifies low-risk patients with pulmonary embolism (PE).
  
  
  METHODS
  Validation study using prospectively collected data.
  
  
  METHODS
  A total of 119 European hospitals.
  
  
  METHODS
  A total of 899 patients diagnosed with PE.
  
  
  METHODS
  The PESI uses 11 clinical factors to stratify patients with PE into five classes (I-V) of increasing risk of mortality. We calculated the PESI risk class for each patient and the proportion of patients classified as low-risk (classes I and II). The outcomes were overall and PE-specific mortality for low-risk patients at 3 months after presentation. We calculated the sensitivity, specificity and predictive values to predict overall and PE-specific mortality and the discriminatory power using the area under the receiver operating characteristic curve.
  
  
  RESULTS
  Overall and PE-specific mortality was 6.5% (58/899) and 2.3% (21/899) respectively. Forty-seven per cent of patients (426/899) were classified as low-risk. Low-risk patients had an overall mortality of only 1.2% (5/426) and a PE-specific mortality of 0.7% (3/426). The sensitivity was 91 [95% confidence interval (CI): 81-97%] and the negative predictive value was 99% (95% CI: 97-100%) for overall mortality. The sensitivity was 86% (95% CI: 64-97%) and the negative predictive value was 99% (95% CI: 98-100%) for PE-specific mortality. The areas under the receiver operating characteristic curve for overall and PE-specific mortality were 0.80 (95% CI: 0.75-0.86) and 0.77 (95% CI: 0.68-0.86) respectively.
  
  
  CONCLUSIONS
  This validation study confirms that the PESI reliably identifies low-risk patients with PE who are potential candidates for less costly outpatient treatment.
authors.affiliation: Division of General Internal Medicine, University Outpatient Clinic, Clinical Epidemiology Center, University of Lausanne, Lausanne, Switzerland. drahomir.aujesky@chuv.ch
authors.forename: D
authors.initials: D
authors.lastname: Aujesky
authors.forename: A
authors.initials: A
authors.lastname: Perrier
authors.forename: P-M
authors.initials: PM
authors.lastname: Roy
authors.forename: R A
authors.initials: RA
authors.lastname: Stone
authors.forename: J
authors.initials: J
authors.lastname: Cornuz
authors.forename: G
authors.initials: G
authors.lastname: Meyer
authors.forename: D S
authors.initials: DS
authors.lastname: Obrosky
authors.forename: M J
authors.initials: MJ
authors.lastname: Fine
mesh_terms: D000368:Aged; D005260:Female; D006305:Health Status Indicators; D006801:Humans; D008297:Male; D008875:Middle Aged; D011336:Probability; D011379:Prognosis; D011446:Prospective Studies; D011655:Pulmonary Embolism / Q000175:diagnosis* / Q000401:mortality; D018570:Risk Assessment / Q000379:methods; D012680:Sensitivity and Specificity