The Hospital Trauma Index

The Injury Severity Score (ISS) is a widely used trauma scoring system which, based on the Hospital Trauma Index (HTI), categorizes injury into six different organ systems. A possible limitation is the equal weight given to each body region, although this equal qualification is not appropriate when predicting mortality. This study was undertaken to determine the impact on mortality of equal injury severity in different body regions. All consecutive multiply injured patients (HTI-ISS ≥ 18) treated over a 4-year period in the University Medical Center Utrecht, the Netherlands, were reviewed. The prognostic value of the HTIISS concerning mortality was assessed, before and after incorporating the presence of relevant injury (HTI ≥ 3) in each separate organ system, with receiver operating characteristics and logistic regression modeling. The HTI-ISS proved to be a good predictor of mortality. In the highest quintile, 55% of the patients died. The area under the curve (AUC) was 0.83 (95% confidence interval [CI] 0.79–0.87). The risk of dying increased 13 times (hazard ratio [HR] 13.2 [6.5–26.8]) once relevant head injury was present. After incorporation of head injury, the prognostic value of the HTI-ISS increased to 0.87 (95% CI 0.84–0.91). Injury in any of the other organ systems did not significantly increase the prognostic value of the HTI-ISS for mortality. The prognostic value of the HTI-ISS for mortality is fairly good. If the weight of head injury in the HTI-ISS is doubled, the predicted probability rises significantly to an AUC of 0.87. It is too far-fetched to change the calculation of the HTI-ISS based on one study, but one should be aware of the impact of relevant injuries to the head. This study confirms the expert opinion that relevant to severe head injury is a special and dominant predictor of mortality in multiply injured patients.