Identification of major trauma using the simplified abbreviated injury scale to estimate the injury severity score: a diagnostic accuracy and validation study.

Background: The Abbreviated Injury Scale (AIS) and Injury Severity Score (ISS) grade the severity of injuries and are useful for trauma audit and benchmarking. However, AIS coding is complex and requires specifically trained staff. A simple yet reliable scoring system is needed. The aim of this study was two-fold. First, to develop and validate a simplified AIS (sAIS) chart centred on the most frequent injuries for use by non-trained healthcare professionals. Second, to evaluate the diagnostic accuracy of the sAIS (index test) to calculate the simplified ISS (sISS) to identify major trauma, compared with the reference AIS (rAIS) to calculate the reference ISS (rISS).

Methods: This retrospective study used data (2013-2014) from the Northern French Alps Trauma Registry to develop and internally validate the sAIS. External validation was performed with data from the Trauma Registry of Acute Care of Lausanne University Hospital, Switzerland (2019-2021). Both datasets comprised a random sample of 100 injured patients. Following the Standards for Reporting of Diagnostic Accuracy Studies 2015 guidelines, all patients completed the rAIS and the sAIS. The sISS and the rISS were calculated using the sAIS and the rAIS, respectively. Accuracy was evaluated with the mean difference between the sISS and the rISS and the Pearson correlation coefficient. A clinically relevant equivalence limit was set at ± 4 ISS points. Precision was analyzed using Bland-Altmann plots with 95% limits of agreement.

Results: Accuracy was good. The mean ISS difference of 0.97 (95% CI, -0.03 to 1.97) in the internal validation dataset and - 1.77 (95% CI, - 3.04 to 0.50) in the external validation dataset remained within the equivalence limit. The Pearson correlation coefficient was 0.93 in the internal validation dataset (95% CI, 0.90-0.95) and 0.82 in the external validation dataset (95% CI, 0.75-0.88). The limits of agreement were wider than the predetermined relevant range.

Conclusions: The sAIS is accurate, but slightly imprecise in calculating the ISS. The development of this scale increases the possibilities to use a scoring system for severely injured patients in settings with a reduced availability of the AIS.

Trial Registration: Retrospectively registered.