Unexpected contribution of moderate traumatic brain injury to death after major trauma

The cardiovascular reflex responses to injury and simple hemorrhage are coordinated in the central nervous system. Coincidental brain injury, which is present in 64% of trauma patients who die, could impair these homeostatic responses. The occurrence of hemorrhagic shock in the patient with head injury is also known to increase mortality. Therefore, there is a potential bidirectional interaction between traumatic brain injury and peripheral injury, which would result in an increased mortality when these two injuries coexist. Our objective was to test the hypothesis that moderate traumatic brain injury is an independent predictor of outcome in patients with multisystem trauma.

We carried out an analysis of the UK Trauma Audit and Research Network Database. Moderate traumatic brain injury was defined as an Abbreviated Injury Scale score of 3. The study population included 2,717 patients with multisystem injury: 378 patients had a moderate brain injury with peripheral injury, and 2,339 patients had extracranial injury alone. Mortality rates for both groups were compared at increasing injury severity.

Moderate brain injury alone was associated with a mortality rate of 4.2%. However, when combined with extracranial injury, the risk of death was double that attributable to extracranial injury alone (odds ratio, 2.08; 95% confidence interval, 1.57-2.77).

This study confirms that the coexistence of moderate traumatic brain injury with extracranial injury is associated with a doubling of the predicted mortality rate throughout the injury severity ranges studied.