Which AIS based scoring system is the best predictor of outcome in orthopaedic blunt trauma patients?

Background: Abbreviated Injury Scale (AIS)-based systems - the Injury Severity Score (ISS), New Injury Severity Score (NISS), and AISmax - are used to assess trauma patients. The merits of each in predicting outcome are controversial. Methods: A large prospective database was used to assess their predictive capacity using receiver operator characteristic curves. Results: In all, 10,062 adult, blunt-trauma patients met the inclusion criteria. All systems were significant outcome predictors for sepsis, multiple organ failure (MOF), length of hospital stay, length of intensive care unit (ICU) admission and mortality (p < 0.0001). NISS was a significantly better predictor than the ISS for mortality (p < 0.0001). NISS was equivalent to the AISmax for mortality prediction and superior in patients with orthopaedic injuries. NISS was significantly better for sepsis, MOF, ICU stay, and total hospital stay (p < 0.0001). Conclusions: NISS is superior or equivalent to the ISS and AISmax for prediction of all investigated outcomes in a population of blunt trauma patients. As NISS is easier to calculate, its use is recommended to stratify patients for clinical and research purposes.