Abbreviated Injury Scale

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Abbreviated Injury Scale

• Measures of severity
• ICE on injury statistics
• Maria Segui-Gomez

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Agenda

• Brief history
• Uses and overuses
• Advantages/limitations over other severity
  measures
• common criticisms

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Disclaimer

• I was a member of the AAAM Injury Scaling
  Committe from 1999-2003 and now I am back on it

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The AIS is

• An anatomically based,
• consensus derived,
• global severity scoring system
• that classifies each injury in every body region
• according to its relative importance on a six
  point ordinal scale

T. Genarelli, AAAM annual meeting 2003
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Purposes of AIS

• Describe injuries anatomically
• Standardize injury terminology
• Rank injuries by severity
• Facilitate comparisons of injury studies

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History

• 1971 AAAM and SAE get together to develop a tool
  that will allow injury and injury severity
  characterization for physicians and motor vehicle
  engineers
• Injury severity defined as a mix of death threat,
  energy dissipation, disability, duration of
  treatment and incidence of injury
• In 1974, first release with approximately 70
  injuries given severity scores ranging 1-6

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• Several revisions leading up to AIS 1985 were
  current format was adopted

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• AIS 1990 (with 1998 update) well extended
• AIS 2005 just released.
• Expansion in format
• Incorporation of Orthopedic Trauma Association
  codes for fractures
• 6.1 (22) 2000 codes (and them some)
• Allows for specification of aspect and others

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Over time things have

• remained constant
• Pre dot injury descriptor
• Post dot severity descriptor
• Severity range 0-6
• Expert assessment of severity

• ..or changed
• Definition of severity narrowed to threat to
  life
• Expanded to non motor vehicle injuries (e.g.,
  burns)
• Expanded to pediatric injuries
• Expanded to include LOC for brain injury only
  exception to anatomic basis

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Overall

• Produced centrally by AAAM
• Used in all in-depth crash investigation efforts
  in US and Europe (NASS CDS, CIREN, CCIS, German
  database) and in many more in other continents
• Bases for motor vehicle regulation in US, Canada,
  Australia, Japan and Europe
• Used in some 1600 papers since 1975 avaliable
  throug Pub Med and many more engineering papers
  not available trhough Pub Med
• Available in English, Spanish, Chinese, French,
  German, Italian
• Certification for coding in place in US plans to
  extend abroad

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Some big helpers

• Mapping from ICD-9-CM to AIS85 introduced AIS to
  massive health-related databases such as hospital
  discharge data
• Updated to AIS1990 (update 1998)
• Other maps available in several Trauma Registry
  software packages
• Its body region classification has been widely
  adopted (maybe until arrival of Barell matrix)

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Common Criticisms

• Expert assement (as in subjective, poor)
• Same severity score does not mean the same in
  different body regions
• Presumes otherwise healthy individual, up to
  standard health care, single injuries
• You have to buy a license
• There is no map for ICD-10

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But

• Not all injuries are sufficiently frequent in
  real world databases
• On actual comparison of AIS and death at hospital
  discharge (as printed in AIS 2005 manual)

Data from NTR -ACS
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And

• Same severity score does not mean the same in
  different body regions ??
• Presumes otherwise healthy individual, up to
  standard health care, single injuries
• You have to buy a license. Yes, 190 each
• There is no map for ICD-10. No, we just finished
  one to AIS-98! Plans to map to AIS05 underway

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Head to Head comparison

• AIS
• Expert assement
• Broader definition of time to death
• Single injury, can combine
• Universal

• ICISS
• Empirically based
• If hospital, death to discharge, if death
  certificate
• Each injury goes in with whichever proportion of
  other injuries are present (and reported)
• Which version? Which country? Which datasource?
  Which year?

Both are anatomically based, assign severity to
some 2000 descriptors, ignore many other
confounders (for death)
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In sum

• No perfect measure
• Not perfect for all and every use
• But at least common language across disciplines
  and countries