Parameters seen on admission:
(1) systolic blood pressure in mm Hg
(2) heart rate in beats per minute
(3) arterial pH
(4) hematocrit in percent
X =
=(0.0158 * (heart rate)) - (0.0113 * (systolic blood pressure)) – (0.0932 * (pH)) – (0.0395 * (hematocrit)) + 32.8738
where:
• In the published abstract the factor for pH is –0.0932. In Maegle et al the factor is +0.0932. The risk associated with pH should be with acidosis.
• When the equation is modeled as written the results do not make sense. A modified equation with (a) the heart rate as a negative weighitng and (b) each weighting multiplied by 10 give better results.
probablility of massive transfusion =
= (1 / (1 + EXP((-1) * X))
Interpretation:
• The cut-off was a probability >= 50%.
• The patients who required transfusion tended to have a higher Injury Severity Score (ISS).
Performance:
• The sensitivity was 87% and specificity 53%.
• The positive predictive value was 75% and negative predictive value 72%.
