Same Abbreviated Injury Scale Values May Be Associated with Different Risks to Mortality in Trauma Patients: A Cross-Sectional Retrospective Study Based on the Trauma Registry System in a Level I Trauma Center.

Cheng-Shyuan Rau,Pao-Jen Kuo,Hsiao-Yun Hsieh,Ching-Hua Hsieh,Peng-Chen Chien,Shao-Chun Wu,Yi-Chun Chen

doi:10.3390/ijerph14121552

Abstract

The Abbreviated Injury Scale (AIS) measures injury severity of a trauma patient with a numeric method for ranking anatomy-based specific injuries. The summation of the squares of the three most severe injuries in the AIS of six predefined body regions comprises the Injury Severity Score (ISS). It assumes that the mortality of a given AIS value is similar across all body regions. However, such an assumption is less explored in the literature. In this study, we aimed to compare the mortality rates of the patients with the same AIS value in different injured body regions in a level I trauma center. Hospitalized adult trauma patients with isolated serious to critical injury (AIS of 3 to 5) between 1 January 2009, and 31 December 2016, from the Trauma Registry System in a level I trauma center were grouped according to the injured body regions (including, the head/neck, thorax, abdomen, or extremities) and were exclusively compared according to their AIS stratum. Categorical data were compared using the two-sided Fisher exact or Pearson chi-square tests. ANOVA with Games-Howell post hoc test was performed to assess the differences in continuous data of the patients with injury in different body regions. The primary outcome of the study was in-hospital mortality. The adjusted odds ratios (AORs) were estimated using a stepwise selection of a multivariable regression model adjusted by controlling the confounding variables such as sex, age, comorbidities, and ISS. Survival curves were estimated with the Kaplan–Meier approach with a corresponding log-rank test. The patients with AIS of 5 for abdomen injury and those with AIS of 3 for extremity injury had a significantly lower odds of adjusted mortality (adjusted odds ratio (AOR) 0.1, 95% confidence interval (CI) 0.01–0.39, p = 0.004 and AOR 0.3, 95% CI 0.15–0.51, p < 0.001, respectively) than that of the patients with head/neck injury. However, the patients with AIS of 4 for extremity injury demonstrated significantly higher odds of adjusted mortality (AOR 8.4, 95% CI 2.84–25.07, p < 0.001) than the patients with head/neck injury. This study found that the risks to mortality in the patients with a given AIS value of serious to critical injury in different injured body regions were not the same, even after controlling for confounding variables such as sex, age, comorbidities, and ISS.

Highlights

The Abbreviated Injury Scale (AIS) was developed in 1971 to measures injury severity of a trauma patient with a numeric method for ranking anatomy-based specific injuries [1]
Because the number of patients with isolated AIS = 5 injury to one body region was too few for a powerful statistical analysis, additional group of patients with AIS = 5 injury to either body region was included and the polytrauma patients were not excluded from the analysis especially for this studied group of patients
Patients with abdomen injury were younger, no significant difference in sex, age, comorbidities, and injury mechanism was noted between the patients with thorax injury and head/neck injury

Summary

Introduction

The Abbreviated Injury Scale (AIS) was developed in 1971 to measures injury severity of a trauma patient with a numeric method for ranking anatomy-based specific injuries [1]. The AIS assesses the severity of the anatomical injury on a six-point ordinal scale ranging from minor (1), moderate (2), serious (3), severe (4), critical (5), to un-survivable injury (6), and served as a fundamental base of many severity scoring systems. The Injury Severity Score (ISS), created by Baker et al. As the scores of these different systems in injury severity assessment are based solely on the AIS, their final scores will be greatly influenced by the accuracy of AIS in determining individual anatomical injury severity. The AIS scores are created according to many dimensions of the injury, including impacted energy, extent of organ damage, threat to life, permanent impairment, and period of management [1]. The mortality of a given AIS value is assumed to be similar across all body regions

Objectives

Methods

Results