Objective: To describe characteristics and outcomes for patients hospitalized with fever, not only patients with fever of unknown origin (FUO).
Methods: Medical records were reviewed for 226 consecutive patients hospitalized in a Japanese referral hospital with fever as one of the clinical problems.
Results: Although the majority of illnesses involved some sort of infection (54%), noninfectious inflammatory diseases, particularly adult Stills disease (n=6) and primary vasculitis syndromes (n=5) including 3 cases of Behçets disease, represented the leading cause in patients who met the definition of FUO [16/51(31%)]. Tuberculosis (n=6) and psychological disorders (n=6) were associated with late diagnosis. However, there was only one patient meeting the definition of FUO among those with a psychological disorder. Among the patients with prolonged fever who did not strictly meet the definition of FUO, there was a considerable number of patients with critical illnesses, such as intra-abdominal abscess, polymyalgia rheumatica, sarcoidosis, ulcerative colitis, Castlemans disease, hematological and solid malignancies, and panhypopituitarism. Drug-induced fever, systemic viral infection and unspecified vasculitis were difficult to definitively diagnose, although these pathologies were suspected as causes of fever. Follow-up of patients without definitive diagnosis at discharge confirmed that the fever subsided spontaneously or the cause of fever was properly treated after diagnosis in every patient and that none died of the underlying febrile illness.
Conclusions: The present findings, from all patients displaying fever at hospitalization, are in agreement with findings from prior FUO series. Strict use of the definition of FUO is thus unwarranted when managing patients with prolonged fever.