Predicting Outcome after Traumatic Brain Injury: Development and International Validation of Prognostic Scores Based on Admission Characteristics
Figure 1
Score Chart for 6 Month Outcome after TBI
Sum scores can be calculated for the core model (age, motor score, pupillary reactivity), the extended model (core + hypoxia + hypotension + CT characteristics), and a lab model (core + hypoxia + hypotension + CT + glucose + Hb). The probability of 6 mo outcome is defined as 1 / (1 + e−LP), where LP refers to the linear predictor in a logistic regression model. Six LPs were defined as follows:
LPcore, mortality = −2.55 + 0.275 × sum score core
LPcore, unfavorable outcome = −1.62 + 0.299 × sum score core
LPextended, mortality = −2.98 + 0.256 × (sum score core + subscore CT)
LPextended, unfavorable outcome = −2.10 + 0.276 × (sum score core + subscore CT)
LPlab, mortality = −3.42 + 0.216 × (sum score core + subscore CT + subscore lab)
LPlab, unfavorable outcome = −2.82 + 0.257 × (sum score core + subscore CT + subscore lab)
The logistic functions are plotted with 95% confidence intervals in Figure 2.