The Abbreviated Injury Scale (AIS) was developed to allow measurement of severity of injury in a standardized, reproducible manner and, along with the Injury Severity Score (ISS), has been widely accepted for that purpose. Recently, the apparent usefulness of the ISS in treating a heterogeneous population as if it were homogeneous has been questioned, with specific concern expressed over its use in determining quality assurance standards.

At this institution the ISS has been proposed as a means of projecting the hospital costs incurred in treating trauma victims. This study was undertaken to investigate the possibility that the methodology used may have similar shortcomings, and to evaluate the ISS as a predictor of length of stay.

Although patients suffering severe brain injury were found to have longer length of stay and higher cost, the ISS was demonstrated to have significant predictive ability when applied to resource utilization. It also has the value of allowing this projection of lengths of stay in the intensive care unit and ward, as well as hospital cost, to be made within 24 hours of admission.