Original Article Predicting Survival after Trauma: a Comparison of TRISS and ASCOT in the Netherlands Sander P.G. Frankema 1 , Michael J.R. Edwards 2 , Ewout W. Steyerberg 3 , Arie B. van Vugt 1 355 European Journal of Trauma 2002 · No. 6 © Urban & Vogel European Journal of Trauma Abstract Background: Evaluating the performance of a trauma system may be attempted by comparing outcome in different trauma populations. Controlling for injury severity is a necessity for such evaluations. We compare two current models for doing so: the “Trauma and Injury Severity Score” (TRISS) and “A Severity Character- ization Of Trauma” (ASCOT). Material and Methods: This study of high-energy trau- ma victims took place in Leiden, the Netherlands, between 1993 and 1998. Using the Hosmer-Lemeshow (HL) test and receiver operator characteristic (ROC) analysis, the TRISS and ASCOT models were compared for calibration and discrimination. Results: 1,024 patients, with an average Injury Severity Score (ISS) of 13.5, were eligible for inclusion. Blunt trau- ma was the predominant cause of injuries. Both mod- els gave accurate, though pessimistic, results in pre- dicting the actual number of fatalities (n = 71). The HL test indicated a sufficient fit for the ASCOT model (p = 0.28) and an insufficient fit (p = 0.02) for TRISS. The ROC curves were nearly identical (0.97). Including age as a linear variable, instead of using the current age groups, resulted in an improved discriminative power of the models. Conclusions: The ASCOT model proved superior over TRISS in its accuracy to estimate of survival chances. This difference was most evident for victims with an estimated survival chance of 60–90%. Future national trauma researchers should therefore collect ASCOT data. Improved ASCOT models could be developed, with age as a linear variable. Key Words Trauma · Prognosis · Mortality · Abbreviated Injury Scale · TRISS · ASCOT Eur J Trauma 2002;28:355–64 DOI 10.1007/s00068-002-1217-9 Introduction Comparison of outcome in injured patients from differ- ent trauma care regions or evaluation of changes in a trauma system is complex, because the trauma popula- tions may differ in injury severity. Adjusting for severity can be done by individually estimating the survival chances (probability of survival [Ps]) for all patients. Hospitals receiving many severely injured patients will show a lower average of estimated chances of survival and higher estimated mortality rates. In recent years, a number of statistical models were developed to predict mortality in trauma patients [1–6]. These methods, based on large patient groups, offer a standard by combining a number of variables, which are thought to influence survival most: vital instability, injury severity, age, and mechanism of trauma (MOT). The aim of this study was to compare two current models which seem suitable for the Dutch situation: the “Trauma and Injury Severity Score” (TRISS) [1] and the “A Severity Characterization of Trauma” (ASCOT) methodology [2]. TRISS and ASCOT differ in the manner in which injuries are described and in the level of detail entered into the equation. This results in a more complex com- 1 Department of General Surgery and Traumatology, Erasmus MC Rotterdam, The Netherlands, 2 Department of General Surgery, Rode Kruis Hospital, The Hague, The Netherlands, 3 Department of Public Health, Erasmus MC Rotterdam, The Nether- lands. Received: April 25, 2002; revision accepted: September 17, 2002