Evaluation of trauma care using TRISS method: the role of adjusted misclassification rate and adjusted w-statistic

The aim of this study is to analyze interaction between misclassification rate and w-statistic and to adjust these parameters to be closer to the truth.Analysis of components of TRISS misclassification rate and w-statistic and actual trauma outcome.The component of false negative (FN) (by TRISS method unexpected deaths) has two parts: preventable (Pd) and non-preventable (nonPd) trauma deaths. Pd represents inappropriate trauma care of an institution; otherwise nonpreventable trauma deaths represents errors in TRISS method. Removing patients with preventable trauma deaths we get an Adjusted misclassification rate: (FP + FN - Pd)/N or (b+c-Pd)/N. Substracting nonPd from FN value in w-statistic formula we get an Adjusted w-statistic: [FP-(FN - nonPd)]/N, respectively (FP-Pd)/N, or (b-Pd)/N).Because adjusted formulas clean method from inappropriate trauma care, and clean trauma care from the methods error, TRISS adjusted misclassification rate and adjusted w-statistic gives more realistic results and may be used in researches of trauma outcome.Major trauma is defined as a severe trauma injury when the patient dies in ED or needs major surgical operation on the head, chest, abdomen or inguinal areas or needs immediate ICU admission [1]. If ISS > 15 major trauma is considered. The incidence of major trauma is around 340 – 522 in one million inhabitants per year, and mortality is still high [2,3]. Trauma patients occupy more hospital beds then all patients from heart diseases, and four times more than patients with cancer [4]. Most often are locomotors injuries, but the main cause of death is head trauma [5-7]. Trauma is still the leading cause of deaths of children in industrialized countries [8]. The rate of preventable trauma deaths in the literature is 30% in nontrauma hospitals, and 1 – 5% in trauma centers. In the past two decades of trauma literature the scoring systems issues are very actual; the three most citied articles in the Journal of Trauma are from the fie