Refining the Association of Fever with Functional Outcome in Aneurysmal Subarachnoid Hemorrhage

Introduction: We analyzed the impact of cause, severity, and duration of fever on functional outcome in patients with aneurysmal subarachnoid hemorrhage (aSAH). Methods: Fever characteristics were analyzed in 584 consecutive patients with aSAH. Fever was defined as core body temperature ≥38.3 °C on ≥2 consecutive days. Subfebrile measurements were those between 37 and 38.2 °C. Febrile and subfebrile loads were the number of hours with fever or subfebrile measurements, respectively. Univariate and multivariate logistic regression models were developed to define predictors of outcome using various categorizations of fever cause, severity, and duration. Results: Febrile measurements were observed in 281/584 (48.1 %) patients, recurring over a mean duration of 2.1 ± 3.0 days. Early fever within 24 and 72 h was encountered in 69 (11.9 %) and 110 (18.9 %) of patients, respectively. An infectious source was discovered in 126 (44.8 %) febrile patients. On univariate analysis, days of fever, febrile load, and fever onset within 24 and 72 h were associated with poor outcome (all p < 0.001); but subfebrile load was not (p = 0.56). On multivariate model constructed with all variables associated with outcome on univariate analyses, days of fever remained independently associated with poor outcome (OR 1.14 of poor outcome per day of fever, 95 % CI 1.06–1.22; p = 0.0006) displacing all other fever measures from the final model. Conclusions: Early onset of fever, number of hours with fever, and especially days of fever are associated with poor functional outcome. Conversely, subfebrile load does not influence clinical outcome. These data suggest prolonged fever should be avoided, but subfebrile temperatures may not justify intervention.