The Abbreviated Injury Scale (AIS), developed by the Association for the Advancement of Automotive Medicine (AAAM) is the most widely used anatomic injury severity scale in the world. However, different user groups have modified the AIS system to fit their needs, and these modifications prevent ready comparison and trending of data collected in these systems in the US and throughout the world. The US currently has 5 AIS based severity systems (NASS-88, NASS-93, AIS-85, AIS-90, NTSB) and two AIS based impairment systems (IIS and FCI) in use, with additional revisions forthcoming. Other modified AIS systems are known to be in use in the U.K. and Japan. The data collected in these systems cannot be accurately combined or compared without re-coding or the use of complex “mapping” programs.

With the increasing use of severity mapping of statewide hospital discharge data (ICD-PCM and soon ICD-IO-CM) and linking of country wide mortality data (ICD-9 and ICD- 10) for engineering use, the relationship of the AIS severity systems to ICD-9/10, ICD-9-CM, and the proposed ICD- IO-CM becomes more important. The recent creation of the national FARS-MCOD database for fatal motor vehicle (MV) injuries, and the mapping of statewide CODES data to NASS format are indicators of future data directions.

This paper compares five severity systems and two impairment systems in terms of purpose, code structure and use and discusses the reasons for the user modifications to these systems. With global “harmonization” encouraging greater sharing of international data, the paper also presents the relationship of the AIS worldwide to the larger scope of worldwide mortality (ICD-9/10) and US reimbursement (ICD-9-CM/lo-CM) classification systems.

To resolve compatibility issues resulting from multiple injury systems, the authors propose a “unified” system for global use, configured by inputs from major AIS “data owners”, users and analysts. Six key attributes of the unified system are:​ (1) Backward compatibility with historical data through “maps” so no data is lost. (2) “Scalable” to allow a simple level of use for developing countries, a more complex level for crash research and a detailed level for clinical hospital use, all with data compatibility. (3) Satisfy the needs of the engineering community for injury location information and aspect, and also the clinical requirement for precise injury description. (4) Integrated interface for overall severity scores, such as MAIS, ISS and NISS*. (5) Coordination with other injury data systems such as the ICD-9/10 mortality systems and ICD-9/10-CM reimbursement systems.*** (6) Establish a structured process to maintain and upgrade the system, on a data compatible basis for the 21” century.

The authors believe that a “unified” system is critical to the preservation of the AIS as a worldwide standard. Unified data can provide a pool of consistent international data to support a variety of important research, prevention and treatment efforts and is essential to satisfy the global needs of the medical and engineering communities.