title: Major causes of fever of unknown origin at Peking Union Medical College Hospital in the past 26 years.
abstract: BACKGROUND
  Despite the recent advances in medicine, fever of unknown origin (FUO) remains a diagnostic and therapeutic challenge even to expert physicians. To increase the knowledge of FUO, we conducted a retrospective study to investigate the causes of FUO and the change of major causes of FUO during the past 26 years.
  
  
  METHODS
  The clinical data were retrospectively analyzed from 997 patients with FUO hospitalized at the Peking Union Medical College Hospital (PUMCH) between January 2004 and October 2010. Furthermore, the results were compared to that reported in previous studies of FUO in PUMCH since 1985.
  
  
  RESULTS
  Of the 997 FUO cases, definite diagnosis was eventually achieved in 797 (79.9%) patients. The most common cause of FUO was infectious diseases (479 cases, 48.0%), with tuberculosis accounting for 45.3% (217/479) of the cases of infections. One hundred and sixty-eight (16.9%) patients were diagnosed with connective tissue diseases, with Still's disease and vasculitis accounted for 31.5% (53/168) and 24.4% (41/168) of this category, respectively. Neoplasms and miscellaneous causes were found in 7.9% (79/997) and 7.1% (71/997), respectively. However, no definite diagnosis had been made in the remaining 200 (20.1%) cases until they were discharged from the hospital.
  
  
  CONCLUSIONS
  During different periods, infectious diseases, especially tuberculosis, were the leading etiology of FUO and the proportion of tuberculosis had no significant difference. While the frequency of neoplasms was descending, the proportion of lymphoma in neoplasm was ascending; the frequency of undiagnosed cases was increasing, but in most FUO cases the causes can be diagnosed eventually after careful analysis of clinical data.
authors.affiliation: Department of Infectious Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100730, China.
authors.forename: Xiao-chun
authors.initials: XC
authors.lastname: Shi
authors.forename: Xiao-qing
authors.initials: XQ
authors.lastname: Liu
authors.forename: Bao-tong
authors.initials: BT
authors.lastname: Zhou
authors.forename: Li-fan
authors.initials: LF
authors.lastname: Zhang
authors.forename: Xiao-jun
authors.initials: XJ
authors.lastname: Ma
authors.forename: Guo-hua
authors.initials: GH
authors.lastname: Deng
authors.forename: Tai-sheng
authors.initials: TS
authors.lastname: Li
authors.forename: Rui-yuan
authors.initials: RY
authors.lastname: Sheng
authors.forename: Ai-xia
authors.initials: AX
authors.lastname: Wang
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003141:Communicable Diseases / Q000150:complications; D003937:Diagnosis, Differential; D005260:Female; D005335:Fever of Unknown Origin / Q000209:etiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D014376:Tuberculosis / Q000150:complications; D055815:Young Adult