title: External validation of models for estimating pretest probability of coronary artery disease among individuals undergoing myocardial perfusion imaging.
abstract: BACKGROUND
  Clinical decisions regarding the appropriateness of noninvasive cardiac imaging among individuals with suspected coronary artery disease (CAD) rely heavily on the pretest probability of coronary artery disease (pCAD), often estimated from clinical prediction models. These models have not been validated among individuals undergoing noninvasive myocardial perfusion imaging (MPI) for suspected CAD. Thus, the objective of this study was to compare the extent of agreement and predictive performance between four published pCAD models among individuals undergoing positron emission tomography (PET MPI).
  
  
  METHODS
  This cross-sectional study performed at a cardiac referral center included 2383 patients with stable symptoms undergoing PET MPI for the evaluation of suspected CAD. pCAD was estimated on a per-patient basis using four distinct pCAD estimation models. All pCAD estimates were calibrated to a common standard to allow fair comparisons of agreement and predictive performance. Pairwise pCAD model disagreement was defined as percent discordance in classifying patients as low versus intermediate pCAD (<10% vs. ≥10%). Predictive performance was quantified by c-statistics with abnormal myocardial perfusion as a binary outcome.
  
  
  RESULTS
  Pairwise pCAD estimates demonstrated non-negligible disagreement with percent discordance between models ranging from 11% to 23%. Agreement worsened when higher thresholds for distinguishing low-intermediate pCAD were employed. All pCAD models demonstrated poor predictive performance for identifying abnormal stress perfusion with c-statistics ranging from 0.554 to 0.616.
  
  
  CONCLUSIONS
  pCAD estimation models showed suboptimal agreement and poor predictive performance in patients undergoing PET MPI. The transportability of pCAD models to MPI patients should be questioned and further evaluated in future studies.
authors: Geisinger Health System, Danville, PA, United States. Electronic address: bawilliams2@geisinger.edu.
authors: Brent A
authors: BA
authors: Williams
authors: New York University School of Medicine, New York, NY, United States.
authors: Joseph A
authors: JA
authors: Ladapo
authors: Coronary Disease Reversal and Prevention Center, Tonawanda, NY, United States.
authors: Michael E
authors: ME
authors: Merhige
mesh_terms: D000368:Aged; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging* / Q000453:epidemiology; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D055414:Myocardial Perfusion Imaging / Q000379:methods*; D049268:Positron-Emission Tomography; D011379:Prognosis; D015203:Reproducibility of Results; D018570:Risk Assessment; D012307:Risk Factors; D015899:Tomography, Emission-Computed, Single-Photon; D014481:United States / Q000453:epidemiology
keywords: Cardiac imaging; Coronary artery disease; Positron emission tomography