Effect of Hypernatremia on Outcomes After severe Traumatic Brain Injury: A Nationwide Inpatient Sample analysis

OBJECTIVE: Induced hypernatremia is frequently used to reduce intracranial pressure in patients with severe traumatic brain injury (TBI). This technique is controversial, and some studies have independently associated hypernatremia with worse outcomes after TBI. We sought to investigate this potential association in a large healthcare database. METHODS: The Nationwide Inpatient Sample was used to obtain data on all adults who had been discharged from 2002 to 2011 with a primary diagnosis of TBI who required mechanical ventilation, intracranial pressure monitoring, or craniotomy/craniectomy. Patients with diabetes insipidus were excluded. The patients with hypernatremia were assigned to the hypernatremia group, and the rest were assigned to the control group. The primary outcome was in-hospital mortality, and the secondary outcomes included the length of stay, nonroutine hospital discharge, total hospital charges, tracheostomy, and gastrostomy placement. RESULTS: A total of 85,579 patients without a diagnosis of hypernatremia (control group) and 4542 patients with a diagnosis of hypernatremia (hypernatremia group) were identified. When controlling for age, comorbidities, gender, and cerebral edema, hypernatremia was associated with an increased rate of in-hospital mortality (odds ratio, 1.51; 95% confidence interval, 1.39-1.65), a longer mean length of stay (23.65 vs. 12.12 days; P < 0.001), an increased rate of nonroutine hospital discharge (odds ratio, 2.58; 95% confidence interval, 2.28-2.92), and greater mean total hospital cost ($227,112 vs. $112,507; P < 0.001). The patients with hypernatremia also had greater rates of tracheostomy and gastrostomy placement. CONCLUSIONS: Hypernatremia was associated with poorer outcomes in patients with severe TBI. This finding warrants further investigation in a prospective, randomized study.