The epidemiology of spontaneous fever and hypothermia on admission of brain injury patients to intensive care units: a multicenter cohort study

Abstract

Object Fever and hypothermia (dysthermia) are associated with poor outcomes in patients with brain injuries. The authors sought to study the epidemiology of dysthermia on admission to the intensive care unit (ICU) and the effect on in-hospital case fatality in a mixed cohort of patients with brain injuries. Methods The authors conducted a multicenter retrospective cohort study in 94 ICUs in the United States. Critically ill patients with neurological injuries, including acute ischemic stroke (AIS), aneurysmal subarachnoid hemorrhage (aSAH), intracerebral hemorrhage (ICH), and traumatic brain injury (TBI), who were older than 17 years and consecutively admitted to the ICU from 2003 to 2008 were selected for analysis. Results In total, 13,587 patients were included in this study; AIS was diagnosed in 2973 patients (22%), ICH in 4192 (31%), aSAH in 2346 (17%), and TBI in 4076 (30%). On admission to the ICU, fever was more common among TBI and aSAH patients, and hypothermia was more common among ICH patients. In-hospital case fatality was more common among patients with hypothermia (OR 12.7, 95% CI 8.4–19.4) than among those with fever (OR 1.9, 95% CI 1.7–2.1). Compared with patients with ICH (OR 2.0, 95% CI 1.8–2.3), TBI (OR 1.5, 95% CI 1.3–1.8), and aSAH (OR 1.4, 95% CI 1.2–1.7), patients with AIS who developed fever had the highest risk of death (OR 3.1, 95% CI 2.5–3.7). Although all hypothermic patients had an increased mortality rate, this increase was not significantly different across subgroups. In a multivariable analysis, when adjusted for all other confounders, exposure to fever (adjusted OR 1.3, 95% CI 1.1–1.5) or hypothermia (adjusted OR 7.8, 95% CI 3.9–15.4) on admission to the ICU was found to be significantly associated with in-hospital case fatality. Conclusions Fever is frequently encountered in the acute phase of brain injury, and a small proportion of patients with brain injuries may also develop spontaneous hypothermia. The effect of fever on mortality rates differed by neurological diagnosis. Both early spontaneous fever and hypothermia conferred a higher risk of in-hospital death after brain injury.