### Description

Velmahos developed a model for predicting the probability of a repeat head CT showing additional findings in a patient with minimal head injury. This can help identify patients who may not need a repeat CT examination. The authors are from Massachusetts General Hospital.

Patient selection: head injury with Glasgow coma score 13, 14 or 15

Parameters:

(1) interval between injury and head CT

(2) age of the patient in years

(3) GCS score

(4) number of lesions on initial CT scan

 Parameter Finding Points interval between injury and CT < 90 minutes 1 >= 90 minutes 0 age of patient in years <= 65 years 0 > 65 years 1 GCS score 15 0 13 or 14 0 number of lesions on initial CT 0 or 1 0 2 or more 1

total score =

= SUM(points for all 4 factors)

Interpretation:

• minimum number of risk factors: 0

• maximum number of risk factors: 4

• The higher the number of risk factors the more likely a repeat CT head scan will be worse.

 Interval Age Number of Lesions GCS Probability >= 90 <= 65 0 or 1 15 2% >= 90 <= 65 0 or 1 13 or 14 5% >= 90 <= 65 2+ 15 5% >= 90 <= 65 2+ 13 or 14 16% >= 90 > 65 0 or 1 15 6% >= 90 > 65 0 or 1 13 or 14 17% >= 90 > 65 2+ 15 18% >= 90 > 65 2+ 13 or 14 44% < 90 <= 65 0 or 1 15 9% < 90 <= 65 0 or 1 13 or 14 28% < 90 <= 65 2+ 15 27% < 90 <= 65 2+ 13 or 14 56% < 90 > 65 0 or 1 15 28% < 90 > 65 0 or 1 13 or 14 57% < 90 > 65 2+ 15 59% < 90 > 65 2+ 13 or 14 83%