title: Overuse of computed tomography pulmonary angiography in the evaluation of patients with suspected pulmonary embolism in the emergency department.
abstract: BACKGROUND
  Clinical decision rules have been developed and validated for the evaluation of patients presenting with suspected pulmonary embolism (PE) to the emergency department (ED).
  
  
  OBJECTIVE
  The objective was to assess the percentage of computed tomographic pulmonary angiography (CT-PA) procedures that could have been avoided by use of the Wells score coupled with D-dimer testing (Wells/D-dimer) or pulmonary embolism rule-out criteria (PERC) in ED patients with suspected PE.
  
  
  METHODS
  The authors conducted a prospective cohort study of adult ED patients undergoing CT-PA for suspected PE. Wells score and PERC were calculated. A research blood sample was obtained for D-dimer testing for subjects who did not undergo testing as part of their ED evaluation. The primary outcome was PE by CT-PA or 90-day follow-up. Secondary outcomes were ED length of stay (LOS) and CT-PA time as defined by time from order to initial radiologist interpretation.
  
  
  RESULTS
  Of 152 suspected PE subjects available for analysis (mean ± SD age = 46.3 ± 15.6 years, 74% female, 59% black or African American, 11.8% diagnosed with PE), 14 (9.2%) met PERC, none of whom were diagnosed with PE. A low-risk Wells score (≤4) was assigned to 110 (72%) subjects, of whom only 38 (35%) underwent clinical D-dimer testing (elevated in 33/38). Of the 72 subjects with low-risk Wells scores who did not have D-dimers performed in the ED, archived research samples were negative in 16 (22%). All 21 subjects with low-risk Wells scores and negative D-dimers were PE-negative. CT-PA time (median = 160 minutes) accounted for more than half of total ED LOS (median = 295 minutes).
  
  
  CONCLUSIONS
  In total, 9.2 and 13.8% of CT-PA procedures could have been avoided by use of PERC and Wells/D-dimer, respectively.
authors.affiliation: Department of Emergency Medicine, University of Pennsylvania, Philadelphia, PA, USA.
authors.forename: Amanda
authors.initials: A
authors.lastname: Crichlow
authors.forename: Adam
authors.initials: A
authors.lastname: Cuker
authors.forename: Angela M
authors.initials: AM
authors.lastname: Mills
mesh_terms: D000046:Academic Medical Centers; D000328:Adult; D000792:Angiography / Q000706:statistics & numerical data*; D015415:Biomarkers / Q000097:blood; D015331:Cohort Studies; D004636:Emergency Service, Hospital; D005260:Female; D005338:Fibrin Fibrinogen Degradation Products / Q000032:analysis*; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D010414:Pennsylvania; D011446:Prospective Studies; D011655:Pulmonary Embolism / Q000097:blood / Q000175:diagnosis / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed / Q000706:statistics & numerical data*; D019564:Unnecessary Procedures / Q000706:statistics & numerical data*; D014505:Urban Population
chemical_list: D015415:Biomarkers; D005338:Fibrin Fibrinogen Degradation Products; C036309:fibrin fragment D