title: Informed prognosis [corrected] after abdominal aortic aneurysm repair using predictive modeling techniques [corrected].
abstract: OBJECTIVE
  To identify the best method for the prediction of postoperative mortality in individual abdominal aortic aneurysm surgery (AAA) patients by comparing statistical modelling with artificial neural networks' (ANN) and clinicians' estimates.
  
  
  METHODS
  An observational multicenter study was conducted of prospectively collected postoperative Acute Physiology and Chronic Health Evaluation II data for a 9-year period from 24 intensive care units (ICU) in the Thames region of the United Kingdom. The study cohort consisted of 1205 elective and 546 emergency AAA patients. Four independent physiologic variables-age, acute physiology score, emergency operation, and chronic health evaluation-were used to develop multiple regression and ANN models to predict in-hospital mortality. The models were developed on 75% of the patient population and their validity tested on the remaining 25%. The results from these two models were compared with the observed outcome and clinicians' estimates by using measures of calibration, discrimination, and subgroup analysis.
  
  
  RESULTS
  Observed in-hospital mortality for elective surgery was 9.3% (95% confidence interval [CI], 7.7% to 11.1%) and for emergency surgery, 46.7% (95% CI, 42.5 to 51.0%). The ANN and the statistical models were both more accurate than the clinicians' predictions. Only the statistical model was internally valid, however, when applied to the validation set of observations, as evidenced by calibration (Hosmer-Lemeshow C statistic, 14.97; P = .060), discrimination properties (area under receiver operating characteristic curve, 0.869; 95% CI, 0.824 to 0.913), and subgroup analysis.
  
  
  CONCLUSIONS
  The prediction of in-hospital mortality in AAA patients by multiple regression is more accurate than clinicians' estimates or ANN modelling. Clinicians can use this statistical model as an objective adjunct to generate informed prognosis.
authors.affiliation: Nuffield Department of Surgery, John Radcliffe Hospital, Oxford, United Kingdom. vassilis@doctors.org.uk
authors.forename: Vassilis Georgiou
authors.initials: VG
authors.lastname: Hadjianastassiou
authors.forename: Leonardo
authors.initials: L
authors.lastname: Franco
authors.forename: Jose M
authors.initials: JM
authors.lastname: Jerez
authors.forename: Iordanis E
authors.initials: IE
authors.lastname: Evangelou
authors.forename: David R
authors.initials: DR
authors.lastname: Goldhill
authors.forename: Paris P
authors.initials: PP
authors.lastname: Tekkis
authors.forename: Linda J
authors.initials: LJ
authors.lastname: Hands
mesh_terms: D017544:Aortic Aneurysm, Abdominal / Q000401:mortality* / Q000601:surgery*; D005260:Female; D006801:Humans; D008297:Male; D015233:Models, Statistical; D016571:Neural Networks, Computer; D011379:Prognosis