Differential performance of TRISS-like in early and late blunt trauma deaths

OBJECTIVES: (1) To independently validate the Trauma and Injury Severity Score-Like (TRISS-Like) model derived by Offner et al. (Revision of TRISS for intubated patients. J Trauma. 1992;32:32-35) in a population of Canadian blunt trauma victims, and (2) to compare the ability of this model to predict mortality in early and late trauma deaths. STUDY POPULATION: Prospective cohort of blunt trauma cases with Injury Severity Score > 12 identified from the Ontario Trauma Registry over a 5-year period. STUDY DESIGN: The TRISS-Like model consisting of age, Injury Severity Score, systolic blood pressure, and best motor response of the Glasgow Coma Scale was evaluated as to its ability to predict mortality by determining the sensitivity, specificity, and the area under the receiver operating characteristic curve. The sample was then divided into early (< or = 7 days) and late mortality subgroups in which model performance was evaluated with respect to time of death. RESULTS: A total of 7,703 patients were included in this analysis. The overall mortality was 12.3%. The TRISS-Like model allowed for assessment of an additional 23% of patients than would standard TRISS and performed with a sensitivity of 97.1%, specificity of 39.8% and an area under the receiver operating characteristic curve of 0.873. Analysis of mortality with respect to time demonstrated that 75% of deaths occurred by day 7. The specificity and receiver operating characteristic area increased in the early (< or = 7 days) subgroup, 46.5% and 0.935, respectively, compared with 20.8% and 0.778 in the late mortality group. CONCLUSIONS: TRISS-Like demonstrated similar performance to that reported with the standard TRISS model but with the additional advantage that it is more generalizable because it can be applied to intubated patients. TRISS-Like demonstrated substantially superior performance in early trauma deaths compared with those that occurred late. This differential performance may be because the model does not include risk factors for late mortality.