title: Derivation of a clinical decision rule to exclude thoracic aortic imaging in patients with blunt chest trauma after motor vehicle collisions.
abstract: BACKGROUND
  Thoracic aortic injury (TAI) is associated with high mortality. It is not practical to evaluate all patients with blunt chest trauma with dedicated aortic imaging. The purpose of this study was to define a group of patients with blunt chest trauma after motor vehicle collision (MVC) that do not require aortic imaging based on information available in the emergency department.
  
  
  METHODS
  This was a secondary analysis of a prospectively-collected database. Consecutive patients with blunt chest trauma after MVC were included. Characteristics of mechanism, examination, and chest radiographic findings were collected for each patient. All patients underwent chest computed tomography (CT), aortography, or both for TAI evaluation. Binary recursive partitioning was used to derive and validate a clinical decision rule to predict exclusion of TAI.
  
  
  RESULTS
  During the study period, 1,096 patients were included, and 22 (2.0%) were diagnosed with TAI. The decision rule for exclusion of TAI included findings from the chest radiograph, incorporating left paraspinous line displacement, obscured aortic knob, and mediastinal widening. The rule resulted in a sensitivity of 86% (95% confidence interval [CI]: 65% to 97%), a specificity of 77% (95% CI: 75% to 80%), a positive predictive value of 7% (95% CI: 4% to 11%), a negative predictive value (NPV) of 99.6% (95% CI: 99.0% to 99.9%), a positive likelihood ratio of 3.8 (95% CI: 1.1-12.9), and a negative likelihood ratio of 0.18 (95% CI: 0.05-0.61). This would potentially reduce aortic imaging by 76% (95% CI: 74% to 79%).
  
  
  CONCLUSIONS
  We report a clinical decision rule with a high NPV for exclusion of TAI. This may standardize the approach to such patients and may reduce the need for CT.
authors.affiliation: Department of Emergency Medicine, Denver Health Medical Center, Denver, Colorado 80204, USA.
authors.forename: Todd C
authors.initials: TC
authors.lastname: Ungar
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Wolf
authors.forename: Jason S
authors.initials: JS
authors.lastname: Haukoos
authors.forename: Debra S
authors.initials: DS
authors.lastname: Dyer
authors.forename: Ernest E
authors.initials: EE
authors.lastname: Moore
mesh_terms: D000063:Accidents, Traffic; D000328:Adult; D001013:Aorta, Thoracic / Q000000981:diagnostic imaging / Q000293:injuries*; D003661:Decision Support Techniques; D004632:Emergency Medical Services / Q000379:methods; D006801:Humans; D015601:Injury Severity Score; D008875:Middle Aged; D015999:Multivariate Analysis; D017410:Practice Guidelines as Topic; D011237:Predictive Value of Tests; D011859:Radiography; D015203:Reproducibility of Results; D012189:Retrospective Studies; D013898:Thoracic Injuries / Q000000981:diagnostic imaging* / Q000209:etiology; D014949:Wounds, Nonpenetrating / Q000000981:diagnostic imaging*