Model of Challen et al for Predicting Potential for Benefit from a Time-Critical Intervention in the Emergency Department (ED)

 

Patient selection: patient in the ED

 

Outcome: benefit from a time-critical intervention

 

Parameters:

(1) pulse in beats per minute

(2) systolic blood pressure in mm Hg

(3) Glasgow Coma Score (GCS)

Parameter	Finding	Points
pulse	<= 70	0
	71 to 110	2.373
	> 110	9.533
systolic blood pressure	> 180 mm Hg	2.888
	121 to 180	0
	100 to 120	1.488
	< 100	3.614
GCS	13 to 15	0
	9 to 12	2.770
	3 to 8	13.28

 

X =

= SUM(points for all 3 parameters)

 

probability of a potential to benefit =

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

 

Interpretation:

• The minimum value of X is 0 which occurs when all of the findings are normal. This gives a probability of 50%.

• The maximum value of X is 26.417 which has a probability of 100%.

• Although there is no factor mentioned in the text, many logistic regression models subtract a constant.

 

Performance:

• The area under the ROC curve was 0.74 in the derivation set and 0.71 in the validation set.