title: Prospective multicenter study of quantitative pretest probability assessment to exclude acute coronary syndrome for patients evaluated in emergency department chest pain units.
abstract: OBJECTIVE
  We compare the diagnostic accuracy of 3 methods--attribute matching, physician's written unstructured estimate, and a logistic regression formula (Acute Coronary Insufficiency-Time Insensitive Predictive Instrument, ACI-TIPI)--of estimating a very low pretest probability (< or = 2%) for acute coronary syndromes in emergency department (ED) patients evaluated in chest pain units.
  
  
  METHODS
  We prospectively studied 1,114 consecutive patients from 3 academic EDs, evaluated for acute coronary syndrome. Physicians collected data required for pretest probability assessment before protocol-driven chest pain unit testing. A pretest probability greater than 2% was considered "test positive." The criterion standard was the outcome of acute coronary syndrome (death, myocardial infarction, revascularization, or > 60% stenosis prompting new treatment) within 45 days, adjudicated by 3 independent reviewers.
  
  
  RESULTS
  Fifty-one of 1,114 enrolled patients (4.5%; 95% confidence interval [CI] 3.4% to 6.0%) developed acute coronary syndrome within 45 days, including 4 of 991 (0.4%; 95% CI 0.1% to 1.0%) patients, discharged after a negative chest pain unit evaluation result, who developed acute coronary syndrome. Unstructured estimate identified 293 patients with pretest probability less than or equal to 2%, 2 had acute coronary syndrome, yielding sensitivity of 96.1% (95% CI 86.5% to 99.5%) and specificity of 27.4% (95% CI 24.7% to 30.2%). Attribute matching identified 304 patients with pretest probability less than or equal to 2%; 1 had acute coronary syndrome, yielding a sensitivity of 98.0% (95% CI 89.6% to 99.9%) and a specificity of 26.1% (95% CI 23.6% to 28.7%). ACI-TIPI identified 56 patients; none had acute coronary syndrome, yielding sensitivity of 100% (95% CI 93.0% to 100%) and specificity of 6.1% (95% CI 4.7% to 7.9%).
  
  
  CONCLUSIONS
  In a low-risk ED population with symptoms suggestive of acute coronary syndrome, patients with a quantitative pretest probability less than or equal to 2%, determined by attribute matching, unstructured estimate, or logistic regression, may not require additional diagnostic testing.
authors.affiliation: Department of Emergency Medicine, Carolinas Medical Center, Charlotte, NC 28323-2861, USA.
authors.forename: Alice M
authors.initials: AM
authors.lastname: Mitchell
authors.forename: J Lee
authors.initials: JL
authors.lastname: Garvey
authors.forename: Abhinav
authors.initials: A
authors.lastname: Chandra
authors.forename: Deborah
authors.initials: D
authors.lastname: Diercks
authors.forename: Charles V
authors.initials: CV
authors.lastname: Pollack
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Kline
mesh_terms: D000208:Acute Disease; D000328:Adult; D002140:California; D002637:Chest Pain / Q000175:diagnosis* / Q000209:etiology*; D003327:Coronary Disease / Q000150:complications* / Q000175:diagnosis*; D003937:Diagnosis, Differential; D004635:Emergency Medicine / Q000379:methods; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data*; D005260:Female; D005500:Follow-Up Studies; D006757:Hospital Units / Q000706:statistics & numerical data*; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009657:North Carolina; D010043:Outcome and Process Assessment, Health Care; D011336:Probability; D011446:Prospective Studies; D012680:Sensitivity and Specificity