Progress toward a new injury severity characterization: Severity profiles

Presented is a new seven-dimensional injury severity profile. The profile includes three physiologic assessments and four variables which express the number, location, and severity of a patient's injuries in terms of ‘Abbreviated injury scale’ values. The physiologic assessments are coded values for the ‘Glasgow coma scale’, systolic blood pressure, and respiratory rate. Also presented are survival-death predictive values of a cluster model based on survival rates of clusters of profiles of 2569 blunt-injured and penetrating-injured patients. The cluster model has a relative information gain ( R) of 0.90. R is a measure of predictive value relative to an infallible predictor. It varies from 0 to 1, the higher the value the better the predictive value. The model had 26 false negatives (deaths predicted to survive) and 35 false positives (survivors predicted to die) giving rise to a false negative rate of 9.3%, a false positive rate of 1.4% and a misclassification rate of 2.4%. The R value and false negative rate are particularly noteworthy, the R value being higher than, and the false negative rate much lower than typical values of 30–40% achieved by TRISS (a combination index based on trauma score, injury severity score and patient age). Also noteworthy is that the clustering was independent of survival/death outcome information and that the good results were achieved even though patient age has not yet been incorporated into the model.