Evolution of the Abbreviated Injury Scale: 1990-2015

Objective: Although the Abbreviated Injury Scale (AIS) was initially developed in the mid-1960s for tracking injury in automotive and aircraft crashes, it has grown to become an internationally recognized scoring system for a variety of traumatic injuries. This shift in focus and advances in organized medical care, combined with feedback from field use and outcome analysis, have resulted in several AIS updates and revisions. This article demonstrates how AIS codes and severities have changed over the last 25 years and investigates the effects of those changes. Methods: Data from each version and update of the AIS dictionary (AIS 1990, AIS 1998, AIS 2005, AIS 2008, and AIS 2015) were analyzed for changes and shifts in injury descriptions, severities, and code counts. Results: The number of AIS codes has increased to improve coding specificity and reliability for a growing number of injury types. There has also been a shift in severities, mainly within the moderate (AIS 2) to severe (AIS 4) range. AIS 1990 was the first version to utilize the 6-digit predot identifier, to add modifiers for pediatric injury, and to substantially expand brain injury codes. AIS 1998 added coding rules and guidelines throughout the dictionary and integrated the Organ Injury Scale scores. The AIS 2005 dictionary added over 400 codes and made significant changes throughout. Fewer changes were made in the AIS 2008 update. AIS 2015 includes descriptions for tissue injuries with loss of soft tissue that do not qualify as amputations, a need identified in military injury analysis. Conclusions: Each updated version of AIS reflects improving medical care and new advances in understanding, measuring, and documenting injury. AIS changes over time reflect its international and cross-domain utilization for describing injury severity and set the standard for how the world now studies traumatic injury.