title: The contribution of the subjective component of the Canadian Pulmonary Embolism Score to the overall score in emergency department patients.
abstract: BACKGROUND
  Clinicians frequently use their experience to determine the pretest probability of pulmonary embolism (PE), although scoring systems are promoted as being more reliable. The Canadian Pulmonary Embolism Score (CPES) combines six objective questions and one subjective question. The CPES has been validated and appears to be useful for risk-stratifying patients. However, research suggests that subjective gestalt performs similarly to the CPES, and the influence of the subjective question on the predictive value of the CPES is not clear.
  
  
  OBJECTIVE
  To determine the test characteristics of the CPES, its subjective question, and the degree to which the predictive value of the CPES is influenced by its individual questions.
  
  
  METHODS
  The authors performed a prospective observational study on a cohort of emergency department patients suspected of having PE. The authors compared patients' CPES results with the diagnosis of PE, calculated the test characteristics of the CPES, and determined the contribution of individual CPES questions to the score's overall predictive value.
  
  
  RESULTS
  Of 607 patients, 61 (10%) had PE. Of low-risk patients (CPES < or =4), 5.54% (n = 449; 95% confidence interval [95% CI] = 3.64% to 8.11%) had PE. The sensitivity (59.0%; 95% CI = 47.4% to 69.8%) and the negative predictive value (94.4%; 95% CI = 92.8% to 95.9%) of the CPES were similar to the sensitivity (53.2%; 95% CI = 40.2% to 65.8%) and negative predictive value (93.5%; 95% CI = 90.7% to 95.5%) of the subjective question alone. In multivariable analysis, nearly all of the predictive value of the CPES was derived from the subjective question.
  
  
  CONCLUSIONS
  The predictive value of the CPES appears to be derived primarily from its subjective component.
authors.affiliation: Department of Emergency Medicine, Massachusetts General Hospital, Boston, MA 02114, USA. ckabrhel@partners.org
authors.forename: Christopher
authors.initials: C
authors.lastname: Kabrhel
authors.forename: Andrew T
authors.initials: AT
authors.lastname: McAfee
authors.forename: Samuel Z
authors.initials: SZ
authors.lastname: Goldhaber
mesh_terms: D000933:Antifibrinolytic Agents / Q000378:metabolism; D015415:Biomarkers / Q000378:metabolism; D001900:Boston; D002170:Canada; D015331:Cohort Studies; D004636:Emergency Service, Hospital; D005260:Female; D005338:Fibrin Fibrinogen Degradation Products / Q000378:metabolism; D005500:Follow-Up Studies; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D008962:Models, Theoretical; D015999:Multivariate Analysis; D011446:Prospective Studies; D011655:Pulmonary Embolism / Q000097:blood / Q000175:diagnosis*; D018570:Risk Assessment / Q000379:methods; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index
chemical_list: D000933:Antifibrinolytic Agents; D015415:Biomarkers; D005338:Fibrin Fibrinogen Degradation Products; C036309:fibrin fragment D