Indicators of central fever in the neurologic intensive care unit

Fever is common in critically ill neurologic patients. Knowledge of the indicators of central fever may allow greater antibiotic stewardship in this era of rapidly developing super-resistant microorganisms.

To develop a model to differentiate central from infectious fever in critically ill neurologic patients with fever of an undetermined cause.

Retrospective data collection from January 1, 2006, through December 31, 2010, at a 20-bed neurologic intensive care unit of a large teaching hospital. Consecutive patients 18 years and older admitted for 48 hours or longer with a core body temperature higher than 38.3 °C on at least 1 measurement for 2 consecutive days. Patients with alternative identified causes of noninfectious fever were excluded. In total, 526 patients were included in the final analysis.

Percentage incidence and odds ratios of variables associated with central fever. Fever was classified as infectious if there was culture growth of a pathogenic species or documented clinical diagnosis of infection treated with antibiotics. Remaining patients were considered to have central fever. Continuous fever lasting longer than 6 hours for 2 or more consecutive days was considered persistent. RESULTS Fever was central in 246 patients (46.8%). Patients with infectious fever were older (mean, 57.4 vs 53.5 years; P = .01) and had a longer length of stay in the neurologic intensive care unit (mean, 12.1 vs 8.8 days; P < .001). Central fever was more likely to occur within 72 hours of admission to the neurologic intensive care unit (76.4% vs 60.7%; P < .001) and tended to be persistent (26.4% vs 18.6%; P = .04). Blood transfusion (odds ratio [OR], 3.06; 95% CI, 1.63-5.76); absence of infiltrate on chest x-ray (3.02; 1.81-5.05); diagnosis of subarachnoid hemorrhage, intraventricular hemorrhage, or tumor (6.33; 3.72-10.77); and onset of fever within 72 hours of hospital admission (2.20; 1.23-3.94) were independent predictors of central fever on multivariable analysis. The combination of negative cultures; absence of infiltrate on chest radiographs; diagnosis of subarachnoid hemorrhage, intraventricular hemorrhage, or tumor; and onset of fever within 72 hours of admission predicted central fever with a probability of .90.

We provide a reliable model to differentiate central fever from infectious fever in critically ill neurologic patients, allowing clinicians to select patients in whom antibiotics may be safely discontinued despite ongoing fever.