Olaussen et al developed models for predicting massive transfusion in a trauma patient based on the shock index. These can help to identify a patient who may require more aggressive resuscitation. The authors are from Monash University, The Alfred Hospital and Ambulance Victoria in Australia.
Patient selection: trauma
Outcome: massive transfusion (>= 5 units of packed red blood cells within the first 4 hours of hospital arrival)
Parameters:
(1) prehospital heart rate in beats per minute
(2) prehospital systolic blood pressure in mm Hg
(3) trauma center heart rate in beats per minute
(4) trauma center systolic blood pressure in mm Hg
prehospital shock index =
= (prehospital heart rate) / (prehospital systolic blood pressure)
trauma center shock index =
= (trauma center heart rate) / (trauma center systolic blood pressure)
X = formulaic model =
= (0.89 * (prehospital shock index)) + (2.16 * (trauma center shock index)) - 5.42
probability of massive transfusion =
= 1 / (1 + EXP((-1) * X))
combination model =
= (0.5 * (prehospital shock index)) + (trauma center shock index)
|
Combination Model
|
Sensitivity
|
Specificity
|
|
>= 1.0
|
88.2%
|
51.9%
|
|
>= 1.2
|
77.3%
|
76%
|
|
>= 1.32
|
72.4%
|
83.5%
|
|
>= 1.5
|
60.3%
|
90.9%
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The maximum Youden index is for combination model >= 1.32.
Performance:
• The area under the ROC curves were 0.83 for both models.
