Fever of unknown origin: a retrospective study of 78 adult patients in Taiwan.

To elucidate the causes of fever of unknown origin (FUO) in Taiwan, we retrospectively analyzed the characteristics of 78 adult patients meeting the classic criteria for fever of unknown origin who were treated at National Taiwan University Hospital from July 1999 through June 2002. Cause of FUO was due to infections in 42.3% of patients, neoplasms in 6.4%, noninfectious inflammatory diseases in 20.5%, and miscellaneous causes in 7.7%, whereas the cause was not established in 23.1% of patients despite every effort. Tuberculosis (14.1%) and acquired immunodeficiency syndrome (7.7%) were the most common causes of infection in patients with FUO, while intraabdominal abscess, infective endocarditis, and tumor were less frequently found. Noninfectious inflammatory diseases were still a very important cause of FUO and were difficult to diagnose. In conclusion, infection remains the most important cause of classic FUO in Taiwan, confirming the findings in previous series. The importance of tuberculosis and AIDS as frequent causes of FUO should be emphasized.