IMP-2005: an injury mortality prediction according to the Abbreviated Injury Scale 2005

Abstract

Background: It has been 45 years since the injury severity score (ISS) was first introduced. The method is flawed in traumatic death prediction but still widely used. Based on the abbreviated injury scale 1998 (AIS_98), there is a relatively more accurate trauma scoring method that assesses the injury mortality prediction (IMP) and trauma mortality prediction model (TMPM) with the regression model. Currently, AIS 2005 (AIS_05) is widely used around the world for trauma scores. This article assesses whether the IMP-2005, an AIS_05 based model, is better than the ISS in predicting trauma results. Methods: Retrospective cohort study is based on the data of 1,239,404 injured patients in the National Trauma Data Bank hospitalized from 2012 to 2014. We established an injury mortality prediction (IMP-2005) model using AIS trauma codes (version 2005) and compared its performance with that of ISS by examining area under the receiver operating characteristic (ROC) curve, the Hosmer-Lemeshow (HL) statistic, and the Akaike information criterion.Results: IMP-2005 behaves significantly both better discrimination (ROCIMP-2005, 0.904; 95% confidence interval (CI), 0.900 to 0.909 and ROCISS, 0.844; 95% CI, 0.839 to 0.850) and calibration (HLIMP-2005, 15.2; 95% CI, 8.5 to20.2 and HLISS, 221; 95% CI, 167 to 268) compared with ISS. Both models showed changes after the extension of gender, age, GCS, mechanism of injury, and mechanical ventilator, but the expansion of IMP-2005 still dominated ISS in every performance.Conclusions: The IMP-2005 provides far improvement in discrimination and calibration compared with the ISS and accurate predictions of mortality. Therefore, we believe that this is a new and feasible scoring method of trauma research and should replace the ISS.