Background: Fever of unknown origin (FUO) remains a challenging problem despite recent advances in diagnostic modalities. The spectrum of disease causing FUO seems to change with time as well as geographical factors. To evaluate the causes of FUO and identify important trends, a retrospective study was performed.
Methods: All adult patients with FUO admitted to the hospital from January 1995 to August 2005 were included. The criteria for diagnosis of FUO were adopted from Durack and Street.
Results: A total of 148 patients (mean age, 42.5 years ; M : F, 70 : 78) were enrolled. Of these, 116 (79%) patients were finally diagnosed with one of the following etiologies: infectious disease (37%), connective tissue disorders (16%), malignancy (14%), and miscellaneous disorders (12%) including Kikuchi’s disease, factitious fever, drug-related fever and thyroiditis. Lymphoma (14%) was the most common cause of FUO, followed by tuberculosis (12.8%) and adult-onset Still’s disease (6.8%). An older age (>50 years), thrombocytopenia, lower CRP level and splenomegaly were predictive factors for malignant disease.. However, 31 patients (21%) did not fit a definite diagnosis despite intensive investigation. Moreover, the proportion (26%) of undiagnosed patients during the period of 2000~2005 was significantly higher than that (13%) during the period of 1995~1999 (p<0.044).
Conclusions: Although infectious disease remains a major cause of FUO, lymphoma was identified as the most common disease entity. The presence of older age, thrombocytopenia, lower CRP and splenomegaly were predictive of malignant disease and therefore require intensive diagnostic work-up.
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