22 Oct

Trauma scores

Trauma score

The role of trauma score in a trauma system is invaluable. It is important in quantifying and stratify patients based on their severity and survival probability.

This score is useful during triage to determine the best centre for transfer and resource use.

Three major scoring systems are used to assess the injured patient. It is classified by anatomic, physiologic and combined.


  • Abbreviated Injury Scale (AIS)
  • Injury Severity Score (ISS)
  • New Injury Severity Score (NISS)
  • American Association for the Surgery of Trauma (AAST) Organ Injury Scale (OIS)


  • Glasgow Coma Scale
  • Revised Trauma Score (RTS)
  • Acute Physiology and Chronic Health Evaluation II Score (APACHE II)

For the interest of our reading, the discussion is based on AIS, ISS and NISS.

Abbreviated Injury Scale (AIS)

AIS uses a scale which divides the injury based on six regions namely head/neck, face, thorax, abdomen, extremities and external injuries. Each injury is assigned a number related to the severity with 1 representing minimal and 6 a fatal injury. This designation forms the basis for the ISS and NISS calculation.

AIS Injury
1 Minor
2 Moderate
3 Serious
4 Severe
5 Critical
6 Lethal

Injury Severity Score (ISS)

This score aims to accurately classify the injuries in the traumatic patient. Although each patient may have variable injuries, the overall survival may be similar. This classification may aid with the designation and transfer plan during the prehospital period. It also helps in predicting the mortality of an injured patient. The calculation consists of the square of highest AIS scores in three most severely injured regions. A high ISS score correlates with the severity and mortality rate. Generally, an ISS score > 15 is considered as major trauma.


ISS Classification Mortality rate
1-8 Minor 1%
9-15 Moderate 2%
16-24 Severe 7%
>24 Very severe >30%


New Injury Severity Score (NISS)

The ISS score does not account the multiple injuries in a single region. Hence, it has the possibility of underestimating the injury severity. Because of this, NISS score was created. The calculation of NISS is similar to the ISS score but uses the three highest AIS scores regardless of the anatomic region. This allows the inclusion of multiple injuries within a single region. Although NISS is an enticing method to calculate severity due to its higher mortality correlation, ISS remain popularly used in the most trauma centre.


There are multiple scoring systems used to classify the severity of injuries. The choice depends on the centre, physician and the aim of use.

More on this here

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