title: Comparison of the risk prediction systems POSSUM and P-POSSUM with the Surgical Risk Scale: A prospective cohort study of 721 patients.
abstract: BACKGROUND
  The outcomes of surgery are subject to variability and difficult to be accurately predicted. Different score systems have been developed to estimating the risk of undergoing a surgical procedure. The aim of this study was to assess the predictive ability of POSSUM and P-POSSUM scoring systems, compared to the Surgical Risk Scale (SRS), in Spanish patients undergoing general surgery.
  
  
  METHODS
  In this prospective observational study, 721 consecutive patients needing a surgical procedure were included. Observed morbidity and mortality after surgery were compared to the expected ones obtained by applying POSSUM, P-POSSUM and SRS.
  
  
  RESULTS
  Mean age was 59.2 years (standard deviation (SD): 17.4 years), 43.5% were women. 616 (85.5%) patients underwent elective general surgery and 105 (14.5%) emergency surgery. The 30-day morbidity was 15.4%. The reintervention rate was 2.1% and mortality was 2.1%. The discrimination ability was excellent in predicting mortality. The Area Under the Curve (AUC) values were: POSSUM: AUC = 0.97, C.I.95%: 0.948-0.992, p < 0.0001; P-POSSUM: AUC = 0.966, C.I.95%: 0.941-0.991, p < 0.0001; SRS: AUC = 0.91, C.I.95%:0.853-0.967, p < 0.0001. POSSUM was also discriminative in the prediction of morbidity (AUC = 0.772, C.I.95%: 0.719-0.826, p < 0.0001). POSSUM predicted morbidity and mortality were higher than the observed ones (p = 0.01 and p = 0.04). Predicted and observed mortality were very similar for P-POSSUM (p = 0.93) and SRS (p = 0.37).
  
  
  CONCLUSIONS
  Expected morbidity and mortality determined by POSSUM score showed values significantly above the observed ones. P-POSSUM and SRS systems were effective in predicting mortality. The SRS application is simple and may contribute to appropriate medical decision making.
authors.affiliation: Department of Surgery, Hospital Moises Broggi, Consorci Sanitari Integral, C/Jacinto Verdaguer 90, E-08970, Sant Joan Despi, Barcelona, Spain. Electronic address: sergio4762@yahoo.es.
authors.forename: Sergio
authors.initials: S
authors.lastname: González-Martínez
authors.affiliation: Department of Clinical Epidemiology, Consorci Sanitari Integral, Av. Josep Molins 29-41, E-08906, L'hospitalet de Llobregat, Barcelona, Spain. Electronic address: Montse.Martin@sanitatintegral.org.
authors.forename: Montserrat
authors.initials: M
authors.lastname: Martín-Baranera
authors.affiliation: Department of Surgery, Hospital Moises Broggi, Consorci Sanitari Integral, C/Jacinto Verdaguer 90, E-08970, Sant Joan Despi, Barcelona, Spain.
authors.forename: Isidro
authors.initials: I
authors.lastname: Martí-Saurí
authors.affiliation: Clinical Nursing, Hospital Dos de Maig, Consorci Sanitari Integral, C/Dos de Maig 301, E-08025, Barcelona, Spain. Electronic address: nborrell@sanitatintegral.org.
authors.forename: Nuria
authors.initials: N
authors.lastname: Borrell-Grau
authors.affiliation: Department of Surgery Hospital Dos de Maig, Consorci Sanitari Integral, C/Dos de Maig 301, E-08025, Barcelona, Spain. Electronic address: recerca@sanitatintegral.org.
authors.forename: José M
authors.initials: JM
authors.lastname: Pueyo-Zurdo
mesh_terms: D000328:Adult; D000368:Aged; D019540:Area Under Curve; D017558:Elective Surgical Procedures / Q000401:mortality*; D004632:Emergency Medical Services / Q000706:statistics & numerical data*; D005260:Female; D006305:Health Status Indicators; D006801:Humans; D008297:Male; D008875:Middle Aged; D009017:Morbidity; D011446:Prospective Studies; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D013030:Spain / Q000453:epidemiology
keywords: General surgery; Risk assessment; Surgical morbidity