Injury Severity Score
Summarizes trauma severity from the three most severely injured body regions.
When to use
Patients with multiple trauma after defining the three body regions with the highest AIS.
Pearls and pitfalls
- ISS adds the squares of the three highest AIS values across body regions.
- Any AIS 6 defines ISS 75 regardless of other regions.
- The same region should not contribute more than one of the three values.
- ISS does not replace clinical assessment or judgment about trauma center need.
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Formula
ISS = sum of the squares of the three highest AIS values; if any AIS is 6, ISS = 75.
Evidence
Anatomic score derived to describe trauma severity and compare outcomes across services.
References
- Baker SP, O'Neill B, Haddon W Jr, Long WB. The injury severity score: a method for describing patients with multiple injuries and evaluating emergency care. J Trauma. 1974;14(3):187-196. doi:10.1097/00005373-197403000-00001
Frequently asked questions
What is Injury Severity Score?
Summarizes trauma severity from the three most severely injured body regions. Patients with multiple trauma after defining the three body regions with the highest AIS.
How is the result calculated?
ISS = sum of the squares of the three highest AIS values; if any AIS is 6, ISS = 75.
How should the result be interpreted?
Anatomic score derived to describe trauma severity and compare outcomes across services.
What are the sources?
Baker SP, O'Neill B, Haddon W Jr, Long WB. The injury severity score: a method for describing patients with multiple injuries and evaluating emergency care. J Trauma. 1974;14(3):187-196.