A Severity Characterization of Trauma (ASCOT)

Components:

(1) variables of the Revised Trauma Score (RTS) upon admission to emergency department (ED): Glasgow Coma Score, systolic blood pressure and respiratory rate

(2) Abbreviated Injury Scale scores

(3) a score for patient's age

(4) coefficients depending on whether trauma was blunt or penetrating

Revised Trauma Score (RTS) Component

Abbreviated Injury Scale (A, B, and C)

For each component, my interpretation of the scoring mechanism ("Each component's value is computed using a generalization of the Pythagorean formula for distance and equals the square root of the sum of the squares of the AIS scores of its associated injuries...Together, the values of A,B, and C describe the number, location and severity of all of a patient's AIS 3, 4 or 5 injuries." Champion et al, 1990) is:

score =

= SQRT(((number of AIS 3 injuries) * (3^2)) + ((number of AIS 4 injuries) * (4^2)) + ((number of AIS 5 injuries) * (5^2)))

where:

• AIS indicates the Abbreviated Injury Scale

• AIS scores of 6 are almost always fatal; patients who may survive have scores that range from 1 to 5. (It is interesting that in the set-asides persons with an AIS = 6 but RTS > 0 had a 22% survival rate, suggesting that perhaps the assignment of 6 as the AIS score was in error, or that very good surgeons were on hand.)

• A fourth component D is included to count the injuries with AIS = 1 or 2, but this is not used for scoring or determining prognosis.

Age Component

Coefficients for TRISS Equation

Note: In the TRISS system all children use the blunt injury coefficients. I could not reference to a similar handling with ASCOT.

Set-Asides

The "set-asides" are patterns of findings where outcomes could be given without the need for calculation.

Calculating Probability of Survival

K =

= (constant) + ((coefficient for G) * (points for Glasgow coma score)) + ((coefficient for S) * (points for systolic blood pressure)) + ((coefficient for R) * (points for respiratory rate)) + ((coefficient for A) * (points for AIS injuries to head, brain and spinal cord)) + ((coefficient for B) * (points for AIS injuries to thorax and neck)) + ((coefficient for C) * (points for AIS injuries to all other sites)) + ((coefficient for age) * (points for age))

probability of survival =

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