The Abbreviated Injury Scale is a catalog of injury lesion descriptions which are indexed by anatomical region and ranked by a numerical scale which is defined to represent "injury severity." It was developed by a panel of experts using a consensus process and did not utilize any quantitative restrospective analyses of trauma data bases. The common notion of the individual AIS "injury severity" values, which range from 1 to 6, is that they are indicative of the "threat to life" that the individual lesion would present to a living individual and the higher this numerical value, the higher the risk of death would be. It is also implied that all lesions ranked ar a specific AIS level would have the same "severity" (threat-to-life) regardless of their anatomical location.

This study examines both of the above notions of the Abbreviated Injury Scale. This is accomplished by analyzing over five hundred cases recorded in the National Accident Sampling System which have been stratified by AIS levels of the two most severe injuries and the anatomical location of each injury. Both the analysis techniques used and the results that assign both an absolute survival rate to each AIS level/body region combination as well as how the compensatory effects of multiple injuries of various severity levels and anatomical locations affect survival are discussed.