Predictors of mortality in adult patients with blunt injuries in New York state: A comparison of the Trauma and Injury Severity Score (TRISS) and theInternational Classification of Disease, Ninth Revision-based Injury Severity Score (ICISS)

Background: The purpose of this study was to determine the statistical mode l that best predicted mortality from blunt trauma using a contemporary popu lation-based database. Methods: 1994-1995 New York State Trauma Registry data for patients with bl unt injuries were used to predict mortality using three statistical models: (1) the original Trauma and Injury Severity Score (TRISS) model based on M ajor Trauma Outcome Study-data, (2) a new TRISS model whose coefficients we re derived using New York data, and (3) the International Classification of Disease, Ninth Revision-based Injury Severity Score (ICISS) with predicted survival values obtained from the Agency for Health Care Policy and Resear ch's Health Care Utilization Project. The models were compared with respect to discrimination (using the C statistic) and calibration (using the Hosme r-Lemeshow [W-L] statistic). In addition, the models were tested to see how well they predicted outcomes for each of the three mechanisms of blunt inj ury. Results: The ICISS model had a significantly higher C statistic (0.878) and a better W-L statistic (29.38) for predicting mortality for all adult pati ents with blunt injuries. The original TRISS model had very poor calibratio n (H-L = 687.38), None of the three models predicted mortality accurately f or victims of motor vehicle crashes or victims of low falls. When separate models were developed for all motor vehicle crashes, low Calls, and other b lunt injuries, the ICISS and New York TRISS models both fit well, although the calibration was marginal in most cases. The ICISS model had a statistic ally significantly higher C statistic for other blunt injuries and for moto r vehicle crashes. The New York TRISS model had better calibration for low falls. Conclusions: The ICISS has promise as an alternative to TRISS, but many mor e comparative studies need to be undertaken using updated TRISS coefficient s. Models should also be developed for mechanisms of injury, not just fur b lunt and penetrating injuries.