title: Estimating injury severity using the Barell matrix.
abstract: OBJECTIVE
  To determine whether the Barell matrix (Inj Prev 2002;8:91-6) could effectively categorize injuries by severity.
  
  
  METHODS
  Injury diagnoses of cases in the 2002 US Nationwide Inpatient Sample were classified according to the Barell matrix. For each cell of the matrix, the authors used ICDMAP-90 to determine the predominant Abbreviated Injury Score (AIS) and body region, and calculated the weighted proportion surviving (bPScell) among patients with any diagnosis in that cell. These findings were used to estimate maximum AIS (bAISmax), ISS (bISS), and the minimum or product of bPScell (bPSmin, bPSprod) for injured patients in the 1996-2000 US National Hospital Discharge Surveys. Case survival was determined for different scores, and outcome models using age, sex, comorbidity, mechanism, and bISS or bPSmin were compared to models using ISS calculated from ICDMAP-90 (mISS) or using ICISS.
  
  
  RESULTS
  Case survival decreased with increasing bAISmax or bISS; survival was closely approximated by bPSmin, and also increased monotonically with bPSprod. Outcome models using bISS or bPSmin were similar to those using mISS or ICISS. An Abbreviated Barell Categorization, with only four groups, was also effective.
  
  
  CONCLUSIONS
  Barell matrix categorization of administrative data allows severity scoring similar to that obtainable with ICDMAP-90 or ICISS.
authors.affiliation: Department of Surgery, Maine Medical Center, Portland, ME, USA. clarkd@mmc.org
authors.forename: D E
authors.initials: DE
authors.lastname: Clark
authors.forename: S
authors.initials: S
authors.lastname: Ahmad
mesh_terms: D017052:Hospital Mortality; D006801:Humans; D015601:Injury Severity Score; D007902:Length of Stay; D011237:Predictive Value of Tests; D016019:Survival Analysis; D014481:United States / Q000453:epidemiology; D014947:Wounds and Injuries / Q000401:mortality*