Trauma Injury Severity Score (TRISS)

Prognoses survival in blunt and penetrating trauma based on RTS, GCS and ISS scores.

In the text below the calculator there is in depth information on the components of the score and on how it is calculated.

TRISS consists of an aggregation of the Glasgow coma scale, the Revised trauma score and the Injury severity score.

It offers survival prognosis in patients presenting to ER with blunt and penetrating trauma.

The RTS and the GCS account for main vital signs whilst the ISS assesses the impact of the traumatic and non-traumatic injury at an anatomical level.

The survival prognosis (as per the original Boyd et al. study from 1987) is computed based on a logarithmic regression equation, as follows:

Survival probability = 1/(1+ e-b)

where b = b0 + b1 x RTS + b2 x ISS + b3 x AgeIndex

The indices used are presented in a table below.

Patient age in years

Revised Trauma Score (RTS)

Systolic blood pressure (BP)
Respiratory rate

Injury Severity Score (ISS)

Head and neck injury
Face injury
Thorax injury
Abdomen injury
Extremities injury
External injury
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Components assessed

The trauma injury severity score was created by Boyd et al. after a 1987 study aimed to integrate the evaluation of trauma in a generic procedure. The TRISS became a standardized approach for the evaluation of outcome of trauma care.

The user is asked to fill in the patient age in years and the components of the RTS and ISS:

A) Revised Trauma Score (RTS):

■ Glasgow Coma Scale (as major ER score with results from 3 to 15);

■ Systolic blood pressure (BP);

■ Respiratory rate.

B) Injury Severity Score (ISS):

■ Head and neck injury;

■ Face injury;

■ Thorax injury;

■ Abdomen injury;

■ Extremities injury;

■ External injury;

The following is the Revised trauma score survival probability table:

Revised Trauma Score
Survival probability
0 2.70%
1 7.10%
2 17.20%
3 36.10%
4 60.50%
5 80.70%
6 91.90%
7 96.90%
7.84 98.80%

The Injury severity score part allows an evaluation of the existent lesions based on the anatomical region they are placed in.

The trauma score obtained varies between 0 and 75. A cut off at 15 was established as a border to major trauma/ polytrauma.

The body regions evaluated separately are:

■ Head and neck: includes injuries to cervical spine;

■ Face: includes facial skeleton, nose, mouth, eyes and ears;

■ Thorax: includes chest injuries to rib cage, thoracic spine and diaphragm;

■ Abdomen: includes abdominal organs and lumbar spine;

■ Extremities: including pelvic skeleton injuries, extremity injuries, sprains, fractures, dislocations;

■ External and other: includes injuries such as lacerations, contusions, burns or hypothermia.

Each of the injuries present is classified as minor, moderate, serious, severe, critical or maximal (un-survivable).

Beside the scores extracted from the RTS and ISS, the trauma injury severity score accounts for the patient age as an AgeIndex (as risk factors for adverse outcome), where patients below 55 are awarded 0 in the formula and patients of 55 and above are awarded 1.

By combining different trauma scores, the triage process in ER is highly standardized resulting in rapid and more accurate decision making.


TRISS formula

The survival prognosis is computed based on a logarithmic regression equation:

Survival probability = 1/(1+ e-b)

where b = b0 + b1 x RTS + b2 x ISS + b3 x AgeIndex


Based on the table with the indices used:

  Blunt Penetrating
b0 -0.4499 -2.5355
b1 0.8085 0.9934
b2 -0.0835 -0.0651
b3 -1.743 -1.136

The two resulting formulas for b are:

■ bBlunt = -0.4499 + 0.8085 x RTS - 0.0835 x ISS - 1.7430 x AgeIndex

■ bPenetrating = -2.5355 + 0.9934 x RTS - 0.0651 x ISS - 1.1360 x AgeIndex


Original source

Boyd CR, Tolson MA, Copes WS. Evaluating trauma care: the TRISS method. Trauma Score and the Injury Severity Score. J Trauma. 1987; 27(4):370-8.

Other references

1. Stewart TC, Lane PL, Stefanits T. An evaluation of patient outcomes before and after trauma center designation using Trauma and Injury Severity Score analysis. J Trauma. 1995; 39(6):1036-40.

2. Singh J, Gupta G, Garg R, Gupta A. Evaluation of trauma and prediction of outcome using TRISS method. J Emerg Trauma Shock. 2011; 4(4): 446–449.

Specialty: Traumatology

Objective: Prognosis

Type: Score

No. Of Variables: 20

Year Of Study: 1987

Abbreviation: TRISS

Article By: Denise Nedea

Published On: March 16, 2017

Last Checked: March 16, 2017

Next Review: March 10, 2023