title: Evaluation of the P-POSSUM mortality prediction algorithm in Australian surgical intensive care unit patients.
abstract: BACKGROUND
  The Physiological and Operative Severity Score for enUmeration of Mortality and Morbidity (POSSUM) is an auditing tool designed to compare surgical outcomes independent of case mix. It uses patient physiological and operative data to predict morbidity and mortality for surgical patients. Thus far most evaluations of the POSSUM algorithm and its modifications have emanated from British hospitals. A single-centre retrospective study was therefore performed to determine the applicability of this tool to the Australian surgical case mix.
  
  
  METHODS
  All surgical patients undergoing a surgical procedure admitted to the Royal Brisbane Hospital intensive care facility in 1999 were reviewed retrospectively. Mortality predictions using the Portsmouth modification of the POSSUM algorithm (P--POSSUM) were compared to the actual outcomes using receiver-operator characteristic curve analysis and the Hosmer and Lemeshow Goodness-of-Fit test.
  
  
  RESULTS
  The records of 229 admissions were reviewed. The area under the receiver-operator characteristic curve was 0.68, significantly greater than 0.5 (P = 0.014). Predicted deaths were significantly greater than actual deaths (50 vs 28, P < 0.001), with over-prediction of death rates in all mortality groupings except the two lowest risk deciles.
  
  
  CONCLUSIONS
  The P-POSSUM algorithm tends to over-estimate mortality in surgical intensive care patients. It may require further calibration before adoption as a surgical audit tool in Australia.
authors.affiliation: Royal Brisbane Hospital, Herston, Queensland, Australia. organ99@bigpond.com
authors.forename: Nicole
authors.initials: N
authors.lastname: Organ
authors.forename: Thomas
authors.initials: T
authors.lastname: Morgan
authors.forename: Balasubramanian
authors.initials: B
authors.lastname: Venkatesh
authors.forename: David
authors.initials: D
authors.lastname: Purdie
mesh_terms: D000368:Aged; D000465:Algorithms; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D007362:Intensive Care Units / Q000592:standards*; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care / Q000379:methods*; D011379:Prognosis; D011793:Queensland / Q000453:epidemiology; D012372:ROC Curve; D012189:Retrospective Studies; D020379:Risk Adjustment / Q000379:methods*; D013514:Surgical Procedures, Operative / Q000401:mortality*