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Estimating injury severity using the Barell matrix
  1. D E Clark1,2,
  2. S Ahmad1
  1. 1Department of Surgery, Maine Medical Center, Portland, ME, USA
  2. 2Harvard Injury Control Research Center, Harvard School of Public Health, Boston, MA, USA
  1. Correspondence to:
 Dr D E Clark
 887 Congress Street, Suite 210, Portland, ME 04102 USA; clarkd{at}


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.

Conclusion: Barell matrix categorization of administrative data allows severity scoring similar to that obtainable with ICDMAP-90 or ICISS.

  • ABC, Abbreviated Barell Categorization
  • AI, anatomic index
  • AIS, Abbreviated Injury Score
  • bAIScell, predominant AIS for a cell of the Barell matrix
  • bAISmax, maximum AIS for a patient estimated using Barell matrix
  • bISS, ISS for a patient estimated using using Barell matrix
  • bPScell, proportion of patients surviving with a diagnosis in a cell
  • bPSmin, minimum bPScell for a patient
  • bPSprod, product of bPScell for a patient
  • CDC, Centers for Disease Control and Prevention
  • ESP, estimated survival probability
  • ICD-9-CM, International Classification of Diseases, Ninth Revision, Clinical Modification
  • ICE, International Collaborative Effort on Injury Statistics
  • ICISS, ICD-9-based Injury Severity Score
  • ISS, Injury Severity Score
  • LOS, length of stay
  • LTC, long term care
  • mAISmax, maximum AIS for a patient estimated using ICDMAP-90
  • mISS, ISS for a patient estimated using using ICDMAP-90
  • NHDS, National Hospital Discharge Survey
  • NIS, Nationwide Inpatient Sample
  • injury severity score
  • barell matrix
  • severity
  • mortality

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  • See linked editorial on p 67

  • Competing interests none.

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