Differences and discrepancies between 2005 and 2008 Abbreviated Injury Scale versions - time to standardise

In order for trauma registry data to be comparable across institutions and trauma systems, the injury classification systems which underpin them must be comparable and consistent. In most trauma registries, injuries are classified using the Abbreviated Injury Scale (AIS) [1,2]. AIS-derived scores such as the Injury Severity Score (ISS) [3] and New Injury Severity Score [4] are used to quantify the severity of (and compare) multiply injured patients; to select patients for inclusion in registries; and as part of the definitions used to describe major trauma. Consequently, consistency of the AIS codesets used is pivotal to the purpose and validity of trauma registries.The Association for the Advancement of Automotive Medicine (AAAM) has updated and maintained the AIS since the early 1970s. Since its initial publication, the AIS codeset has expanded and evolved over several editions. The current version of the AIS (AIS08) [2] is a 2008 update of the greatly expanded 2005 edition (AIS05) [1]. The changes implemented between AIS05 and AIS08 are known to be comparatively minor [5,6]. However, the effect of these changes on actual datasets has not been assessed.Between the 2005 and 2008 AIS releases, the AAAM released an unknown number of periodic updates. These contained individual AIS dictionary pages on which one or more AIS codes had been updated, with the intent that they could replace earlier versions of the pages in users' AIS05 dictionaries. However, it was not always clear which codes were updated on each page, despite this being crucial for users of electronic versions of the AIS. Also, if users purchased AIS dictionaries during this gradual update process or did not update their dictionaries over time, it is possible that not all AIS05 or AIS08 dictionaries in use contain the same codesets or coding instructions.Consequently, we aimed to identify all of the changes made to the AIS codeset since 2005. We therefore evaluated all of the codeset updates (additions,