Mortality in patients presenting with fever of unknown origin

Few data exist on the contemporary prognosis of patients presenting with fever of unknown origin (FUO).The data of 436 adult immunocompetent patients presenting with FUO between 2000 and 2010 and followed for at least 6 months were analyzed, with a focus on FUO-related deaths. The following variables were assessed in survivors and non-survivors: age, underlying diagnosis, and, in a nested case-control design, fever periodicity, selected laboratory parameters (including peripheral blood counts, enzymes, and inflammatory markers) and organomegaly.Thirty FUO-related deaths occurred (6·9%). Malignancy accounted for 11% of fevers but for 60% of deaths. Especially non-Hodgkin lymphoma carried a disproportionally high death toll. In the non-malignant categories, fatality rates were below 6%. All patients discharged without diagnosis in spite of ample investigations (n = 164) survived. Besides malignancy, age, continuous (as opposed to episodic) fever, anaemia, leucopenia, LDH levels, and hepatomegaly were associated with mortality.Fatality rates of FUO have continuously declined over the past decades. Malignancy, including lymphoma, remains a cardinal cause of death. Patients with FUO discharged without diagnosis survive.