AIS derived scores are generated through automated translation of the ICD diagnoses using a computer software package that links to the ICDMap tables. Though an ICDMAP conversion program is not a perfect tool for providing precise information on injury severity, it allows scoring of injury when the number of cases makes it impractical to code medical records.
Data from trauma registries that provide ISS are only reliable if trained abstractors who accurately capture all patient injuries assign AIS scores and ISS. Similarly, the accuracy of ISS derived from a mapping algorithm will be dependent on the quality of ICD coding data available in the database to which it is being applied. Researchers should recognize that in many systems ICD coding is done for billing or for other non-trauma specific purposes, and therefore may not be as comprehensive as data from trauma registries. Researchers using the ICDMap algorithm must ensure that ICD diagnoses are reliably coded in the database that will be used; the algorithm cannot accurately assign ISS if the ICD codes are not assigned accurately.