title: Can prehospital Modified Early Warning Score identify non-trauma patients requiring life-saving intervention in the emergency department?
abstract: OBJECTIVE
  We aim to investigate whether prehospital Modified Early Warning Score (MEWS) can identify non-trauma patients requiring life-saving intervention (LSI) within 4 h of presentation to the ED.
  
  
  METHODS
  It was a prospective study of non-trauma ED patients by ambulance who were 16 years or older from 1 to 27 November 2013. Prehospital MEWS was calculated according to vital signs measured by the ambulance crew. Data on patients' demographics, triage category, LSI within 4 h of ED presentation and 24 h mortality were retrieved. LSI was defined as emergency interventions to airway, breathing and circulation, emergency procedures and medications administered. The performance of prehospital MEWS was analysed with sensitivity, specificity, predictive values (PV), likelihood ratios (LR) and the receiver operating characteristic curve.
  
  
  RESULTS
  Recruited during the study period were 1493 patients. The median age was 78 years. Of the patients, 49.9% belonged to critical, emergent or urgent triage categories. LSI was required in 321 patients (21.5%). Thirteen died within 24 h of ED presentation. The area under the receiver operating characteristic curve of prehospital MEWS relating to LSI was 0.72 (95% confidence interval 0.69 to 0.75). The sensitivity, specificity, positive PV, negative PV, positive LR and negative LR were 0.57, 0.76, 0.40, 0.87, 2.43 and 0.56, respectively, when prehospital MEWS  ≥3 was chosen as the cut-off value.
  
  
  CONCLUSIONS
  Prehospital MEWS is useful in identifying non-trauma patients requiring LSI within 4 h of ED presentation. This may in turn enhance the triage accuracy in the ED in addition to clinical assessment.
authors.affiliation: Accident and Emergency Department, Queen Mary Hospital, Hong Kong SAR, China.
authors.forename: Siu Chung
authors.identifier: http://orcid.org/0000-0003-0169-9899
authors.initials: SC
authors.lastname: Leung
authors.affiliation: Emergency Medicine Unit, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China.
authors.forename: Ling Pong
authors.initials: LP
authors.lastname: Leung
authors.affiliation: Emergency Medicine Unit, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China.
authors.forename: Kit Ling
authors.initials: KL
authors.lastname: Fan
authors.affiliation: Accident and Emergency Department, Queen Mary Hospital, Hong Kong SAR, China.
authors.forename: Wai Lam
authors.initials: WL
authors.lastname: Yip
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004632:Emergency Medical Services; D004636:Emergency Service, Hospital; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012372:ROC Curve; D012151:Resuscitation; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D055986:Vital Signs; D055815:Young Adult
keywords: ambulance; critical illness; emergency medical service; prognosis; sensitivity and specificity