Abbreviated injury scale - (AIS)

The AIS was originally designed to stratify victims of motor vehicle crashes.

On its own its not designed to provide any outcome prediction. It forms the basis of the ISS.

It has undergone six revisions since its initial first description in 1971

AIS - 90 has 1300 individual injuries.

The AIS injury severity values are consensus-derived and range from 1 (minor) to 6 (fatal). Only blunt injuries were included in the first AIS.


Injury AIS score
1 Minor
2 Moderate
3 Serious
4 Severe
5 Critical
6 Unsurvivable

Limitations of AIS:

  • Score 5 and 6 represent the "threat to life" associated with an injury and are not intended to provide a comprehensive measure of severity.
  • AIS - 90 makes no provision for open or comminuted femoral fractures, important for functional outcome, less important in predicting mortality
  • AIS on its own is unable to predict mortality or outcomes.
  • AIS assigned rather than derived viz inter and intra rater error.
  • AIS not a true scale (ie difference between AIS 1 and 2 is not the same as between AIS 4 and 5).

Looking up the scales

The AIS scales for particular injuries were developed by the Association for the Advancement of Automotive Medicine (AAAM) (see link below).

The scales are very similar to the Organ Injury Scales developed by the Organ Injury Scaling Committee of the American Association for the Surgery of Trauma. Also available at

Predicting outcome after multiple trauma: which scoring system?; Injury, Volume 35, Issue 4, April 2004, Pages 347-358; M. N. Chawda , F. Hildebrand , H. C. Pape and P. V. Giannoudis

Committee on Medical Aspects of Automotive Safety. Rating the severity of tissue damage. JAMA. 1971;215:277-286

Association for the Advancement of Automotive Medicine, Committee on Injury Scaling. The Abbreviated Injury Scale—1990 Revision (AIS-90). Des Plains, IL: Association for the Advancement of Automotive Medicine; 1990. - The Association for the Advancement of Automotive Medicine (AAAM)

Last updated 14/09/2004
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