Patient selection:
(1) The age was 10 years of age or greater.
(2) The percent of body surface area with second and third degree burns > 30%.
Data used for equations:
(1) age in years
(2) percent body surface area with second and third degree burns (as number from 0 to 100)
(3) grade of inhalation injury (see previous section, above):
|
Inhalation Injury
|
Grade
|
|
none
|
0
|
|
mild
|
1
|
|
moderate
|
2
|
|
severe
|
3
|
Regression Equation
Z for regression equation =
= (-7.696) + (0.090 * (age in years)) + (0.078 * (percent BSA burned)) + (1.751 * (inhalation injury grade))
probability of mortality =
= EXP(Z) / (1 + Exp(Z))
Modified Baux Burn Score
modified burn score =
= (age) + (percent BSA burned) + (20 * (inhalation injury grade))
The correlation between burn score and mortality rate is given in Figure 6, page 61.
Equations matching score to mortality risk (derived in JMP) are:
|
Burn Score
|
Equation for Mortality Rate
|
|
0 to 72.99
|
(0.0001209 * ((score) ^ 2)) – (0.00924 * (score)) + 0.177
|
|
73 to 108
|
(0.019245 * (score)) – 1.28
|
|
> 108
|
(-0.000062 * ((score) ^ 2)) + (0.01926 * (score)) – 0.507
|
Limitation:
• In the middle linear range the scores vary from about 70 to 110 (40 point change) while mortality rate changes from 20-90% (70 point change). Thus a small change in score can have large effect on the mortality rate.
