### Description

Demetriades et al developed a discriminant function to predict mortality in a patient with isolated head injury. The authors are from the University of Southern California Los Angeles.

Parameters:

(1) Glasgow coma score (GCS)

(3) type of injury

(4) age in years

 Parameter Finding Points Glasgow coma score 3 1 4 to 8 2 9 to 12 3 13 to 15 4 head AIS injury 1 or 2 1 3 2 4 3 5 4 type of injury blunt 0 penetrating 1 age of the patient <= 55 years 0 > 55 years 1

Z =

= (-2.740 * (points for GCS)) + (1.306 * (points for head AIS)) + (2.73 * (points for type of injury)) + (1.096 * (points for age)) + 1.04686

probability of death =

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

where:

• I suspect that the constant in the equation should be (-1.04686) but the above expression is how it is given in the paper.

A second discriminant function was defined for patients with a GCS from 4 to 8:

X =

= (-0.741 * (GCS)) + (1.036 * (points for head AIS)) + (2.375 * (points for type of injury)) + (1.415 * (points for age)) - 0.56219

probability of death =

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