Injury Severity Score (ISS)

The Injury Severity Score (ISS) is a medical scoring system to assess trauma severity. It is based on the Abbreviated Injury Scale (AIS), which grades the severity of individual injuries from 0 (minor) to 6 (unsurvivable). ISS is the sum of the squares of the highest AIS grades for three different body regions. It is used to predict mortality, morbidity, and hospitalization time after trauma. This score is not accurate if multiple injuries are sustained in the same body region; in that case, only the highest AIS score is used for that region.