title: Poor performance of the modified early warning score for predicting mortality in critically ill patients presenting to an emergency department.
abstract: BACKGROUND
  This study was undertaken to validate the use of the modified early warning score (MEWS) as a predictor of patient mortality and intensive care unit (ICU)/ high dependency (HD) admission in an Asian population.
  
  
  METHODS
  The MEWS was applied to a retrospective cohort of 1 024 critically ill patients presenting to a large Asian tertiary emergency department (ED) between November 2006 and December 2007. Individual MEWS was calculated based on vital signs parameters on arrival at ED. Outcomes of mortality and ICU/HD admission were obtained from hospital records. The ability of the composite MEWS and its individual components to predict mortality within 30 days from ED visit was assessed. Sensitivity, specificity, positive and negative predictive values were derived and compared with values from other cohorts. A MEWS of !4 was chosen as the cut-off value for poor prognosis based on previous studies.
  
  
  RESULTS
  A total of 311 (30.4%) critically ill patients were presented with a MEWS !4. Their mean age was 61.4 years (SD 18.1) with a male to female ratio of 1.10. Of the 311 patients, 53 (17%) died within 30 days, 64 (20.6%) were admitted to ICU and 86 (27.7%) were admitted to HD. The area under the receiver operating characteristic curve was 0.71 with a sensitivity of 53.0% and a specificity of 72.1% in addition to a positive predictive value (PPV) of 17.0% and a negative predictive value (NPV) of 93.4% (MEWS cut-off of !4) for predicting mortality.
  
  
  CONCLUSIONS
  The composite MEWS did not perform well in predicting poor patient outcomes for critically ill patients presenting to an ED.
authors.affiliation: Department of Emergency Medicine, Singapore General Hospital, Singapore.
authors.forename: Le Onn
authors.initials: le O
authors.lastname: Ho
authors.affiliation: Department of Clinical Research, Singapore General Hospital, Singapore.
authors.forename: Huihua
authors.initials: H
authors.lastname: Li
authors.affiliation: Department of Emergency Medicine, Singapore General Hospital, Singapore.
authors.forename: Nur
authors.initials: N
authors.lastname: Shahidah
authors.affiliation: Department of Emergency Medicine, Singapore General Hospital, Singapore.
authors.forename: Zhi Xiong
authors.initials: ZX
authors.lastname: Koh
authors.affiliation: Department of Emergency Medicine, Singapore General Hospital, Singapore.
authors.forename: Papia
authors.initials: P
authors.lastname: Sultana
authors.affiliation: Department of Emergency Medicine, Singapore General Hospital, Singapore ; Office of Clinical Science, Duke-NUS Graduate Medical School, Singapore.
authors.forename: Marcus Eng
authors.initials: ME
authors.lastname: Hock Ong
keywords: Emergency department; Modified early warning score; Outcomes; Triage