The ISS is calculated based on the Abbreviated Injury Scale (AIS), which classifies injuries by body region and assigns a severity score ranging from 1 (minor) to 6 (unsurvivable). The ISS considers the three most severe injuries across different body regions. The scores of these injuries are squared and summed to derive the ISS:
\[ \text{ISS} = A^2 + B^2 + C^2 \]
where A, B, and C are the AIS scores of the three most severe injuries. The ISS ranges from 0 to 75, with higher scores indicating more severe injuries.
