title: Estimation of mortality and morbidity risk in vascular surgery using POSSUM and the Portsmouth predictor equation.
abstract: BACKGROUND
  The Physiological and Operative Severity Score for enUmeration of Mortality and morbidity (POSSUM) is a simple scoring system previously validated in general surgical patients which enables estimation of the risk of complications and death after operation. The Portsmouth predictor equation (P-POSSUM) is a modification that may result in more accurate prediction of death than POSSUM. The aim of this study was to test the validity of POSSUM and P-POSSUM in patients undergoing major arterial surgery in a specialist unit.
  
  
  METHODS
  Physiological and operative severity scores in 221 patients undergoing elective and emergency arterial surgery in a pure vascular practice under a single consultant were recorded prospectively. Observed morbidity and mortality rates were compared with the rates predicted by POSSUM and P-POSSUM using a linear method of analysis.
  
  
  RESULTS
  The POSSUM equation overestimated deaths with this analysis but the mortality rate estimated by P-POSSUM was not significantly different from the observed death rate. The risk of morbidity predicted by POSSUM was not significantly different from the observed complication rate.
  
  
  CONCLUSIONS
  The POSSUM methodology combined with the P-POSSUM adjustment for death allows satisfactory prediction of mortality and morbidity rates in patients undergoing vascular surgery.
authors.affiliation: Vascular Surgical Unit, Derriford Hospital, Derriford Road, Plymouth PL6 8DH, UK.
authors.forename: M J
authors.initials: MJ
authors.lastname: Midwinter
authors.forename: M
authors.initials: M
authors.lastname: Tytherleigh
authors.forename: S
authors.initials: S
authors.lastname: Ashley
mesh_terms: D006801:Humans; D009017:Morbidity; D011237:Predictive Value of Tests; D018570:Risk Assessment / Q000379:methods*; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D015996:Survival Rate; D014652:Vascular Diseases / Q000601:surgery*; D014656:Vascular Surgical Procedures / Q000401:mortality*