title: [An analysis of etiologies of fever of unknown origin in 372 patients].
abstract: OBJECTIVE
  To analyze the etiology of fever of unknown origin (FUO).
  
  
  METHODS
  A total of 372 patients with FUO who hospitalized in Capital Medical University Affiliated Beijing Friendship Hospital were retrospectively analyzed from January 2003 to August 2013. All the patients were divided into two groups: group A (January 2003 - December 2007) and group B (January 2008-August 2013). Diagnosis rate, duration of hospitalization (days) and time to diagnosis between the two groups were artificially compared.
  
  
  RESULTS
  Of the 372 FUO cases, 336 were positively diagnosed with a diagnosis rate of 90.3%. Infectious diseases were still the primary causes of FUO (60.2%), including 72 cases (32.1%) of tuberculosis. Connective tissue diseases accounted for 12.9% of the FUO cases, malignancies were 8.3%, and miscellaneous diseases were 8.9%. Yet thirty six patients (9.7%) could not be confirmed until they were discharged from hospital. The duration of fever in patients with malignancies was longer than that with infectious diseases [60.0 (30.0, 90.0) days vs 30.0 (20.0, 60.0) days, P = 0.003]. Time to diagnosis of connective tissue disease and malignancies was longer than infectious diseases [(12.0(7.3, 18.8) days and 11.0 (7.0, 18.0) vs 5.0 (3.0, 8.0) days, both P values = 0.000]. The duration of hospitalization in group A was longer than that of group B [17.0(12.0, 30.0) days vs 14.0(10.0, 20.0) days, P = 0.000]. The diagnosis rate and time to diagnosis of group A were similar with those of group B. The proportion of connective tissue diseases in group A was higher than group B (18.1% vs 9.2%,χ(2) = 6.201, P = 0.013) . The proportion of infectious disease, malignancies and miscellaneous diseases was not significantly different between the two groups.
  
  
  CONCLUSIONS
  Infectious diseases are the major causes of FUO, and the most common cause is tuberculosis. Connective tissue diseases and malignancies are the second and third causes of FUO. The duration of fever and time to diagnosis are significantly different between the different origins.
authors.affiliation: Department of Infectious Diseases, Beijing Friendship Hospital, Capital Medical University, Beijing 100050, China.
authors.forename: Qiuping
authors.initials: Q
authors.lastname: Shi
authors.affiliation: Department of Infectious Diseases, Beijing Friendship Hospital, Capital Medical University, Beijing 100050, China. Email: 15910938286@163.com.
authors.forename: Chao
authors.initials: C
authors.lastname: Wang
authors.affiliation: Department of Infectious Diseases, Beijing Friendship Hospital, Capital Medical University, Beijing 100050, China.
authors.forename: Dinghua
authors.initials: D
authors.lastname: Xu
authors.affiliation: Department of Infectious Diseases, Beijing Friendship Hospital, Capital Medical University, Beijing 100050, China.
authors.forename: Fengwu
authors.initials: F
authors.lastname: Li
authors.affiliation: Department of Infectious Diseases, Beijing Friendship Hospital, Capital Medical University, Beijing 100050, China.
authors.forename: Aimin
authors.initials: A
authors.lastname: Ren
authors.affiliation: Department of Infectious Diseases, Beijing Friendship Hospital, Capital Medical University, Beijing 100050, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Wang
authors.affiliation: Department of Infectious Diseases, Beijing Friendship Hospital, Capital Medical University, Beijing 100050, China.
authors.forename: Shuwen
authors.initials: S
authors.lastname: Zhang
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005335:Fever of Unknown Origin / Q000209:etiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D055815:Young Adult