Base deficit-based predictive modeling of outcome in trauma patients admitted to intensive care units in Dutch trauma centers.

BACKGROUND: Worldwide, the base deficit is available as an objective indicator of acid base status. We used the base deficit as a measure of physiologic derangement in a Trauma and Injury Severity Score (TRISS)-like model as a predictor for outcome in trauma patients.
METHODS: We prospectively recorded data of 349 consecutive trauma patients admitted to the intensive care unit and calculated Revised Trauma Score, Injury Severity Score and Abbreviated Injury Scale, and TRISS and correlated them with the simultaneously determined base deficit value. The delta base deficit is introduced, which is the absolute difference of the base deficit from its normal range (-2 to 2). A statistical model analogous to the TRISS model was designed in which the physiologic disturbance reflected by the Revised Trauma Score was replaced by the delta base deficit [Base Excess Injury Severity Scale (BISS) model]. Calculating the area under the curve (AUC) of the respective receiver operating characteristic curve compared these two models. Finally, the BISS model was validated in a patient group from another tertiary referral hospital in which similar data were recorded prospectively.
RESULTS: We demonstrated a significant correlation between the delta base deficit and the calculated trauma scoring systems. Moreover, the delta base deficit is significantly correlated with mortality. The BISS performed better than the TRISS did when evaluated by the AUC of the receiver operating characteristic curves (AUC 0.806 vs. 0.803, respectively). Validation in an independent prospectively compiled dataset from another referral center showed comparable and even better results (AUC 0.891 vs. 0.885, respectively).
CONCLUSIONS: The performance of our proposed BISS model was superior to that of the TRISS model in the populations under investigation. Nevertheless, given the ease of assessment and the objective value of the base deficit, it may be considered as a good method to predict outcome and evaluate care of trauma patients. Whether this can be translated to trauma patients in general needs further investigation.