Etiology and Resource Use of Fever of Unknown Origin in Hospitalized Children

BACKGROUND: Fever of unknown origin (FUO) is a well-known pediatric presentation. The primary studies determining the causes of prolonged fever in children were performed 4 decades ago, before major advances in laboratory and diagnostic testing. Given that the distribution of diagnosed causes of adult FUO has changed in recent decades, we hypothesized that the etiology of FUO in children has concordantly changed and also may be impacted by a definition that includes a shorter required duration of fever. METHODS: diagnosis of fever, a documented fever duration >7 days before admission, and a previous physician evaluation of each patient's illness. RESULTS: A total of 1164 patients were identified, and of these, 102 met our inclusion criteria for FUO. Etiologic categories included "infectious" (42 out of 102 patients), "autoimmune" (28 out of 102 patients), "oncologic" (18 out of 102 patients), and "other" or "unknown" (14 out of 102 patients). Several clinical factors were statistically and significantly different between etiologic categories, including fever length, laboratory values, imaging performed, length of stay, and hospital costs. CONCLUSIONS: Unlike adult studies, the categorical distribution of diagnoses for pediatric FUO has marginally shifted compared to previously reported pediatric studies. Patients hospitalized with FUO undergo prolonged hospital stays and have high hospital costs. Additional study is needed to improve the recognition, treatment, and expense of diagnosis of prolonged fever in children.