The process of determining the Injury Severity Score (ISS) involves a systematic evaluation of injuries sustained by an individual. This evaluation relies on assigning Abbreviated Injury Scale (AIS) scores to each injury, which reflects the relative severity of that specific injury. The body is divided into six regions: head/neck, face, chest, abdomen, extremities (including pelvis), and external. Only the highest AIS score in each body region is considered. The ISS is then calculated by summing the squares of the three highest AIS scores from different body regions. For example, if an individual has an AIS score of 3 in the head region, 2 in the abdomen, and 1 in an extremity, the ISS would be calculated as (32 + 22 + 12) = 14.
This scoring methodology provides a standardized measure of overall injury severity, which is critical for several reasons. It facilitates objective comparison of injury burdens across different patient populations and allows for the evaluation of trauma care effectiveness. Historically, the development of the ISS has provided a valuable tool for research, enabling studies on injury patterns, treatment outcomes, and the impact of preventative measures. Its use in trauma registries and clinical audits also drives continuous improvement in patient care by highlighting areas where system-level interventions can be most effective.
