Objectives: To study and report the outcome of in-patient trauma cases based on the Trauma and Injury Severity Scoring (TRISS) method and compare the outcome with the registry data from the Major Trauma Outcome Study (MTOS).
Material and Method: A descriptive study was performed by retrospective data collection. From 1 January 2002 to 31 December 2002, all admitted trauma patients in the Accident and Emergency Unit, Department of Surgery, Faculty of Medicine, Khon Kaen University were included in the present study. Survival analysis was completed for all of the patients.
Statistical analysis: TRISS method and W, M and Z-statistics (Z-score) on the basis of definitive outcome-based evaluation (DEF) method for comparing with MTOS data.
Results: The majorities of patients were men (76.85%) and mean age was 30.81 years. One hundred and ninety five patients (96.06%) sustained blunt trauma, the vast majority resulting from motor vehicle crashes. The observed survivors were 182, whereas the expected survivors were 183.582. The W, M and Z-statistics were -0.779, 0.843 and -0.493 respectively.
Conclusion: Z-score -0.493 indicated no statistical difference between observed and expected survivors.

Keywords: Injury severity score, Revised trauma score, Trauma and injury severity score, Abbreviated injury score, Trauma, Outcome, Probability of survival, Major trauma outcome study