title: The quest for a universal definition of polytrauma: a trauma registry-based validation study.
abstract: BACKGROUND
  A pilot validation recommended defining polytrauma as patients with an Abbreviated Injury Scale (AIS) score greater than 2 in at least two Injury Severity Score (ISS) body regions (2 × AIS score > 2). This study aimed to validate this definition on larger data set. We hypothesized that patients defined by the 2 × AIS score > 2 cutoff have worse outcomes and use more resources than those without 2 × AIS score > 2 and that this would therefore be a better definition of polytrauma.
  
  
  METHODS
  Patients injured between 2009 and 2011, with complete documentation of AIS by New South Wales Trauma Registry and 16 years and older were selected. Age and sex were obtained in addition to outcomes of ISS, hospital length of stay (LOS), intensive care unit (ICU) admission, ICU LOS, and mortality. We compared demographic characteristics and outcomes between patients with ISS greater than 15 who did and did not meet the 2 × AIS score > 2 definition. We then undertook regression analyses (logistic regression for binary outcomes [ICU admission and death] and linear regression for hospital and ICU LOS) to compare outcomes for patients with and without 2 × AIS score > 2, adjusting for sex and age categories.
  
  
  RESULTS
  In the adjusted analyses, patients with 2 × AIS score > 2 had twice the odds of being admitted to the ICU compared with those without 2 × AIS score > 2 (odds ratio, 2.5; 95% confidence interval [CI], 2.2-2.8) and 1.7 times the odds of dying (95% CI, 1.4-2.0; p < 0.001 for both models). Patients with 2 × AIS score > 2 also had a mean difference of 1.5 days longer stay in the hospital compared with those without 2 × AIS score > 2 (95% CI, 1.4-1.7) and 1.6 days longer ICU stay (95% CI, 1.4-1.8; p < 0.001 for all models).
  
  
  CONCLUSIONS
  Patients with 2 × AIS score > 2 had higher mortality, more frequent ICU admissions, and longer hospital and ICU stay than those without 2 × AIS score > 2 and represents a superior definition to the definitions for polytrauma currently in use.
  
  
  METHODS
  Diagnostic test/ criteria, level III.
authors.affiliation: From the Division of Surgery (N.E.B., Z.J.B.), Department of Traumatology, John Hunter Hospital, The University of Newcastle, Newcastle, New South Wales; National Centre for Epidemiology Population Health (C.D.E.), The Australian National University, Canberra, Australia.
authors.forename: Nerida E
authors.initials: NE
authors.lastname: Butcher
authors.forename: Catherine
authors.initials: C
authors.lastname: D'Este
authors.forename: Zsolt J
authors.initials: ZJ
authors.lastname: Balogh
mesh_terms: D015998:Abbreviated Injury Scale; D000293:Adolescent; D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D007902:Length of Stay; D008297:Male; D008875:Middle Aged; D009104:Multiple Trauma / Q000175:diagnosis / Q000453:epidemiology*; D009517:New South Wales / Q000453:epidemiology; D012042:Registries; D015599:Trauma Severity Indices