Modifying effects of alcohol use and age on the predictive performance of prehospital shock index for functional and survival outcomes in severe trauma patients

This study investigated whether the prehospital shock index (SI) could predict clinical outcomes in trauma patients, with or without pre-injury alcohol consumption, and whether this predictive capacity varied by age. We conducted a retrospective study on severe trauma patients transported to a level-1 trauma center by emergency medical services from 2015 to 2021. Our primary exposure was abnormal SI, defined as an SI ≥0.9, with in-hospital mortality and poor functional outcomes as study outcomes of interest. Multivariable logistic regression analysis estimated the effect of SI on clinical outcomes. Our findings indicated a significant association between abnormal SI and poor functional outcomes in all trauma patients (adjusted odds ratio: 2.15; 95%confidence interval: 1.41–3.28), notably pronounced in the older age group (adjusted odds ratio: 3.56; 95% confidence interval: 1.55–8.30). However, no association was found with in-hospital mortality. Importantly, among severe trauma patients who did not consume alcohol, abnormal SI was significantly associated with poor functional outcomes, irrespective of age, and with increased in-hospital mortality exclusively in the older age group. Thus, abnormal SI significantly predicted clinical outcomes in non-alcohol-consuming severe trauma patients, with the predictive power for in-hospital mortality being specifically significant in older, non-alcohol-consuming patients.