Clinical features and outcomes of patients with fever of unknown origin: a retrospective study

Few studies have reported the long-term clinical outcome of patients discharged with undiagnosed fever of unknown origin (FUO). In this study, the clinical features and outcomes of patients with unexplained fever were explored to improve our understanding of FUO.

Patients diagnosed with FUO at admission and discharged without final diagnoses after systematic examination in the department of infectious diseases at Peking Union Medical College Hospital between 2004 and 2010 were followed up by telephone. Medical records were reviewed, and the clinical features and outcomes of patients for whom follow-up data were available were summarized.

Between 2004 and 2010, 58 patients with follow-up data, who were diagnosed with FUO at admission and did not have a final diagnosis at discharge, were enrolled in this study. The median duration of follow-up was 518 (0.4-830) weeks, and the fever duration was 24.6 (6.7-763.2) weeks. Final diagnoses were established in 11 cases (19%), and the diagnostic methods included clinical diagnosis, diagnostic therapy, genetic screening and biopsy pathology. The fever in 35 patients (60%) subsided during hospitalization or after discharge. Their condition was stable and self-limited after long-term follow-up, and they were ultimately thought to be cured. Two patients had periodic fever during prolonged observation: one patient needed intermittent use of nonsteroidal antiinflammatory drugs (NSAIDs), and the other needed intermittent use of NSAIDs and a steroid. Ten patients died during follow-up, with 9 deaths being caused by severe and worsening conditions related to the febrile illness.

Long-term follow-up should be performed for patients with undiagnosed FUO. Some patients can obtain a definitive diagnosis by repeated multiple invasive examinations and diagnostic treatment. Most patients have a self-limited illness, and their prognosis is good.