A new definition of major trauma enhances mortality prediction in trauma care.

• In a study of over 2.6 million patients, 22.4% were classified as having “new major trauma” (nmt+) by combining injury severity and trauma team actions.
• Nmt+ identified 29% more in-hospital deaths and 26% more 24-hour deaths compared to the traditional injury severity score (ISS) alone.

This new classification provides superior predictive power (AUROC 0.83) for 24-hour mortality, crucial for surgical decision-making.

• Nmt+ had the lowest negative likelihood ratio (0.16), indicating better identification of survivors.