The TRISS methodology has been widely used as to compare trauma patient outcomes. A recent modification - TRISS-like analysis - allows inclusion of intubated patients. It was hypothesized that the development of coefficients utilizing data from patients within the region being reviewed (Ontario) would provide a better tool. The Comprehensive Data Set of the Ontario Trauma Registry was accessed, which contains data on severely injured patients (ISS > 12) from all 11 lead trauma hospitals in the province. Three year's data were obtained, and checked for accuracy and completeness. TRISS-like analysis was performed using the previously published coefficients. New coefficients were then derived, using regression analysis on the Ontario patient data. 5,258 of 6389 files were complete and eligible for analysis.

TRISS-like analysis resulted in an expected mortality of 21.2% (1115.6/5258) with a z score for the entire province of -14.102. Individual hospital scores were all negative (fewer deaths than expected), and 9/11 hospital scores were <-1.96 (statistically significant). The new coefficients were markedly different from those previously published, and their application resulted in an overall z score of 0.000. Institutional scores ranged from -3.309 to +4.686, with two hospitals <-1.96 and one > + 1.96. The old coefficients predicted many more deaths than occurred in all of the hospitals. The new coefficients proved quite accurate overall in predicting outcomes, and identified one institution with significantly more deaths than would have been predicted for other hospitals in the province.