title: Head multidetector computed tomography: emergency medicine physicians overestimate the pretest probability and legal risk of significant findings.
abstract: OBJECTIVE
  This study focuses on clinically assigned prospective estimated pretest probability and pretest perception of legal risk as independent variables in the ordering of multidetector computed tomographic (MDCT) head scans. Our primary aim is to measure the association between pretest probability of a significant finding and pretest perception of legal risk. Secondarily, we measure the percentage of MDCT scans that physicians would not order if there was no legal risk.
  
  
  METHODS
  This study is a prospective, cross-sectional, descriptive analysis of patients 18 years and older for whom emergency medicine physicians ordered a head MDCT.
  
  
  RESULTS
  We collected a sample of 138 patients subjected to head MDCT scans. The prevalence of a significant finding in our population was 6%, yet the pretest probability expectation of a significant finding was 33%. The legal risk presumed was even more dramatic at 54%. These data support the hypothesis that physicians presume the legal risk to be significantly higher than the risk of a significant finding. A total of 21% or 15% patients (95% confidence interval, ±5.9%) would not have been subjected to MDCT if there was no legal risk.
  
  
  CONCLUSIONS
  Physicians overestimated the probability that the computed tomographic scan would yield a significant result and indicated an even greater perceived medicolegal risk if the scan was not obtained. Physician test-ordering behavior is complex, and our study queries pertinent aspects of MDCT testing. The magnification of legal risk vs the pretest probability of a significant finding is demonstrated. Physicians significantly overestimated pretest probability of a significant finding on head MDCT scans and presumed legal risk.
authors.affiliation: CHRISTUS Spohn Memorial Hospital, EM Residency Program, Corpus Christi, TX 78405, USA. jerry@jrbaskerville.com
authors.forename: Jerry Ray
authors.initials: JR
authors.lastname: Baskerville
authors.forename: John
authors.initials: J
authors.lastname: Herrick
mesh_terms: D001291:Attitude of Health Personnel; D003430:Cross-Sectional Studies; D004635:Emergency Medicine / Q000295:instrumentation / Q000331:legislation & jurisprudence / Q000379:methods; D004636:Emergency Service, Hospital / Q000331:legislation & jurisprudence / Q000706:statistics & numerical data; D006257:Head / Q000000981:diagnostic imaging*; D006801:Humans; D008318:Malpractice / Q000706:statistics & numerical data*; D061330:Multidetector Computed Tomography / Q000706:statistics & numerical data; D011336:Probability; D011446:Prospective Studies; D012306:Risk; D018709:Statistics, Nonparametric