Trauma Severity Scores

Abbreviated Injury Scale (AIS)

  • Introduced in 1969
  • Injuries ranked 1-6 (1 minor and 7 unsurvivable)

AIS Score | Injury

  • 1: Minor

  • 2: Moderate

  • 3: Serious

  • 4: Severe

  • 5: Critical

  • 6: Unsurvivable

  • AIS ranking system is used to create an ISS score

Injury Severity Score (ISS)

  • An anatomic scoring system that grades the severity of an injury as a whole
  • 6 body regions each given its own AIS score
  • Top 3 AIS scores squared and added together to give final ISS score
  • ISS is automatically 75 if any AIS is 6 (unsurvivable)
  • Rising ISS score does correlate with mortality
  • ISS >25 indicates a severe injury
    • Should be considered for transfer to a trauma centre
  • ISS >40 indicates a life-threatening injury

Disadvantages of ISS

  1. Any error in AIS increases the ISS
  2. Does not weight body areas independently
  3. Many different injury patterns give the same ISS score
  4. Only one score per body area is allowed – excludes multiple injuries within one area

Body Region | Injury Description | AIS | Square of Top 3

  • Head & Neck: Cerebral contusion | 3 | 9
  • Face: No injury | |
  • Chest: Flail chest | 4 | 16
  • Abdomen: Liver laceration | 4 | 16
  • Extremity: Femur fracture | 3 |
  • External: No injury | 0 |
  • Total ISS score | | | 41

NISS

  • Modification to the ISS
  • Allows top AIS scores to come from the same body segment
    • E.g., Splenic, pancreatic, and liver injuries are scored separately and can be used individually to generate the NISS score disregarding lesser injuries elsewhere
  • This is more realistic in determining the patient’s survival
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