Delta shock index predicts injury severity, interventions, and outcomes in trauma patients: A 10-year retrospective observational study

Abstract

BACKGROUND

Most trauma occurs among young male subjects in Qatar. We examined the predictive values of the delta shock index (DSI), defined as the change in the shock index (SI) value from the scene to the initial reading in the emergency unit (i.e., subtracting the calculated SI at admission from SI at the scene), at a Level 1 trauma center.

AIM

To explore whether high DSI is associated with severe injuries, more interventions, and worse outcomes [i.e., blood transfusion, exploratory laparotomy, ventilator-associated pneumonia, hospital length of stay (HLOS), and in-hospital mortality] in trauma patients.

METHODS

A retrospective analysis was conducted after data were extracted from the National Trauma Registry between 2011 and 2021. Patients were grouped based on DSI as low (≤ 0.1) or high (> 0.1). Data were analyzed and compared using χ² and Student’s t-tests. Correlations between DSI and injury severity score (ISS), revised trauma score (RTS), abbreviated injury scale (AIS), Glasgow coma scale (GCS), trauma score-ISS (TRISS), HLOS, and number of transfused blood units (NTBU), were assessed using correlation coefficient analysis. The diagnostic testing accuracy for predicting mortality was determined using the validity measures of the DSI. Logistic regression analysis was performed to identify predictors of mortality.

RESULTS

This analysis included 13212 patients with a mean age of 33 ± 14 years, and 24% had a high DSI. Males accounted for 91% of the study population. The trauma activation level was higher in patients with a high DSI (38% vs 15%, P = 0.001). DSI correlated with RTS (r = -0.30), TRISS (r = -0.30), NTBU (r = 0.20), GCS (r = -0.24), ISS (r = 0.22), and HLOS (r = 0.14) (P = 0.001 for all). High DSI was associated with significantly higher rates of intubation, laparotomy, ventilator-associated pneumonia, massive transfusion activation, and mortality than low DSI. For mortality prediction, a high DSI had better specificity, negative predictive value, and negative likelihood ratio (77%, 99%, and 0.49%, respectively). After adjusting for age, emergency medical services time, GCS score, and ISS, multivariable regression analysis showed that DSI was an independent predictor of mortality (odds ratio = 1.9; 95% confidence interval: 1.35-2.76).

CONCLUSION

In addition to sex-biased observations, almost one-quarter of the study cohort had a higher DSI and were mostly young. High DSI correlated significantly with the other injury severity scores, which require more time and imaging to be ready to use. Therefore, DSI is a practical, simple bedside tool for triaging and prognosis in young patients with trauma.

Keywords: Delta shock index; Trauma; Injury severity scores; Interventions; Outcomes

Core Tip: The delta shock index (DSI) is defined as the change of SI value from the scene to the initial reading in the emergency unit (i.e., subtracting calculated SI at admission from SI at the scene). Among young trauma patients, high DSI is associated with severe injuries, more interventions, and worse outcomes (i.e., blood transfusion, exploratory laparotomy, ventilator-associated pneumonia, hospital length of stay, and in-hospital mortality). Apart from gender-biased observation, almost one-quarter of the study cohort had a higher DSI and were mostly young. High DSI correlated significantly with the other injury severity scores that need more time and imaging to be ready to use. Therefore, DSI is a practical, simple bedside tool for triaging and prognosis in young, injured patients.