New Injury Severity Score (NISS)
New Injury Severity Score (Osler 1997): the sum of squares of the three most severe AIS injuries regardless of body region (0-75).
Open the calculator → Runs in your browser. Data leaves only if you deliberately send a problem report from the interactive tool.
Example
- Highest AIS
- 6
- Second-highest AIS
- 3
- Third-highest AIS
- 2
Result: NISS 75: an AIS 6 (unsurvivable by convention) forces the maximal score; three worst AIS 6, 3, 2.
The tool opens with these values already filled in. Replace them with your own.
What the result means
- Score
- sum of squares of the three highest AIS severities (1-6) regardless of body region; any AIS 6 forces the maximal 75. Range up to 75.
- Departure
- unlike ISS, the three worst injuries need not be in three different regions, so multiple severe injuries in one region all count. NISS >= 16 marks major trauma.
What you enter
- Highest AIS (1-6)
- Second-highest AIS (1-6; a partial total is reported as a floor)
- Third-highest AIS (1-6; a partial total is reported as a floor)
How this is calculated
Osler T, Baker SP, Long W. A modification of the injury severity score that both improves accuracy and simplifies scoring. J Trauma. 1997;43(6):922-925. Read the source ↗
A reference and educational tool. Not medical, legal, or financial advice, and not a substitute for clinician judgment.