before use in lieu of a mortality endpoint. Scoring systems developed to evaluate the severity of an injury, such as the APACHE score, have been proposed as the basis for endpoints in trials on trauma. The applicability of these scores as surrogate endpoints has been the subject of considerable debate.
The existing trauma indexing systems have contributed a great deal to the triage of trauma patients and to the development of systems for assessment of quality of care (Champion et al., 1996, 1990, 1989, 1983, 1981; Copes et al., 1990, 1988; Gennarelli et al., 1994, 1989; Sacco et al., 1988, 1984); however, the current trauma indexing systems are inadequate for use in the evaluation of future research (Brenneman et al., 1998; Demetriades et al., 1998; Hoyt, 1998; Roorda et al., 1996; Rutledge and Osler, 1998; Rutledge et al., 1998). The injury severity score (ISS) does not accurately stratify patients according to injury because it was not designed to evaluate penetrating injury and is inaccurate in its ability to categorize head injury. The ISS was developed to categorize blunt injuries sustained in motor vehicle accidents (American Association for Automotive Medicine, 1985). In addition, there may be reason to believe that injuries as defined by ISS do not correlate with the actual demand for resources. There are also problems with the ability of physiologic indexing systems, such as the Revised Trauma Score (RTS), to predict resource need. Casualties with scores that imply a minor injury may have penetrating abdominal injuries that will nonetheless require surgery.
There are also problems with the trauma and injury severity score (TRISS) assessment methodology, which has become the benchmark for the evaluation of trauma care. The TRISS model functions as follows:
The probability of survival Ps is computed by the following equation:
where bn are regression coefficients obtained from the large multithousand patient database that the American College of Surgeons (Baker et al., 1974; Champion et al., 1980a,b, 1981; Flora, 1978; Walker and Duncan, 1967) has collected for over 15 years and analyzed by regression analysis.
Comparison of the predicted outcome with the realized outcome (Z) is calculated by: