Trauma and Injury Severity Score (TRISS)

Components:

(1) Revised Trauma Score (RTS) upon admission to emergency department (ED) as described above, but multiplying the coded values by a weighting factor

(2) Injury Severity Score (ISS) based on final diagnoses (described above)

(3) score for patient's age

(4) coefficients based on blunt versus penetrating trauma

Revised Trauma Score (RTS) Component

revised trauma score = RTS =

= (0.9368 * (points for Glasgow coma score)) + (0.7326 * (points for systolic blood pressure)) + (0.2908 * (points for respiratory rate))

Injury Severity Score (ISS) Component

injury severity score =

= ((highest AIS score) ^ 2) + ((second highest AIS score) ^ 2) + (( third highest AIS score) ^ 2)

where:

• AIS indicates the Abbreviated Injury Scale

• AIS scores range from 1 to 5.

• The maximum ISS is 75.

Age Component

Coefficients for TRISS Equation

where:

• MTOS = Major Trauma Outcome Study, using data submitted through 1986

• Pediatric patients are scored using the blunt trauma coefficients, irrespective of trauma mode (page 373, Boyd 1987)

Calculating Probability of Survival

B =

= B0 + (B1 * RTS) + (B2 * ISS) + (B3 * (age points))

probability of survival =

= 1 / (1 + EXP ((-1) * B))

Limitations:

• Some researchers have found problems with the accuracy of the TRISS method.

• It may be necessary to develop different coefficients for different populations of patients or if it using at different institutions.