Demographic and clinical risk factors associated with hospital mortality after isolated severe traumatic brain injury: a cohort study

Vijay Krishnamoorthy, Monica S. Vavilala, Brianna Mills, Ali Rowhani-Rahbar

Traumatic brain injury (TBI) is a major public health problem and a leading cause of death worldwide. A paucity of literature exists on risk factors for mortality in isolated severe TBI, a condition that is distinct from severe TBI in the setting of multisystem trauma. We determined risk factors for in-hospital mortality in this patient population. We conducted a retrospective cohort study using data from the National Trauma Databank from 2008-2012 to study all patients admitted with a diagnosis of severe TBI, excluding children, patients with non-isolated TBI, transfers, and hospitalization <48 h. We used multivariable Poisson regression to analyze the association between demographic, clinical, and facility-level characteristics and in-hospital mortality. A total of 41,590 patients were included in our analysis. The cumulative incidence of in-hospital mortality was 10.2 %. In multivariable analysis, older age (RR 3.92, 95 % CI 3.54-4.34), male gender (RR 1.17, 95 % CI 1.09-1.25), admission hypotension (RR 1.83, 95 % CI 1.61-2.09), the need for mechanical ventilation (RR 4.18, 95 % CI 3.64-4.80), higher injury severity score (RR 1.86, 95 % CI 1.41-2.45), and poor initial neurologic grade (RR 3.06, 95 % CI 2.74-3.43) were associated with a higher risk for mortality. Admission hypotension and the need for mechanical ventilation were possible modifiable risk factors associated with increased in-hospital mortality following isolated severe TBI. Although risk factors for mortality are similar in isolated and non-isolated TBI, the underlying etiologies for hypotension and respiratory failure are likely different in both conditions and require further exploration.