title: The Waterlow score for risk assessment in surgical patients.
abstract: BACKGROUND
  Perioperative scoring systems aim to predict outcome following surgery and are used in preoperative counselling to guide management and to facilitate internal or external audit. The Waterlow score is used prospectively in many UK hospitals to stratify the risk of decubitus  ulcer development. The primary aim of this study was to assess the potential value of this existing scoring system in the prediction of mortality and morbidity in a general surgical and vascular cohort.
  
  
  METHODS
  A total of 101 consecutive moderate to high risk emergency and elective surgical  patients were identified through a single institution database. The preoperative Waterlow score and outcome data pertaining to that admission were collected. The discriminatory power of the Waterlow score was compared against that of the American Society of Anesthesiologists (ASA) grade and  the Portsmouth Physiological and Operative Severity Score for the enUmeration of Mortality and morbidity (P-POSSUM).
  
  
  RESULTS
  The inpatient mortality rate was 17% and the 30-day morbidity rate was 29%. A statistically significant association was demonstrated between the preoperative Waterlow  score and inpatient mortality (p<0.0001) and 30-day morbidity (p=0.0002). Using a threshold Waterlow score of 20 to dichotomise risk, accuracies of 0.84 and 0.76 for prediction of mortality and morbidity were demonstrated. In comparison with P-POSSUM, the preoperative Waterlow  score performed well on receiver operating characteristic analysis. With respect to mortality, the area under the curve was 0.81 (0.80-0.85) and for morbidity it was 0.72 (0.69-0.76). The ASA grade achieved a similar level of discrimination.
  
  
  CONCLUSIONS
  The Waterlow score  is collected routinely by nursing staff in many hospitals and might therefore be an attractive means of predicting postoperative morbidity and mortality. It might also function to stratify perioperative risk for comparison of surgical outcome data. A prospective study comparing these risk  prediction scores is required to support these findings.
authors: East and North Hertfordshire NHS Trust, UK.
authors: C C
authors: CC
authors: Thorn
authors: M
authors: M
authors: Smith
authors: O
authors: O
authors: Aziz
authors: T C
authors: TC
authors: Holme
mesh_terms: D000368:Aged; D017558:Elective Surgical Procedures / Q000401:mortality*; D004638:Emergency Treatment / Q000401:mortality*; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D007902:Length of Stay / Q000706:statistics & numerical data; D008297:Male; D008875:Middle Aged; D011300:Preoperative Care / Q000401:mortality; D012372:ROC Curve; D018570:Risk Assessment / Q000379:methods; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D014656:Vascular Surgical Procedures / Q000401:mortality*