Why Do We Still Use the Term FUO?

The renewed discussion and debate on the subject of fever of unknown origin (FUO) have brought me some discomfort after reading the article of Vanderschueren et al¹ and accompanying editorial by Bryan.² I believe that in this age of advanced medical science, the use of the term FUO should have been eliminated years ago. The term FUO sometimes tends to shortcut the need of thorough evaluation for a patient as if this were a real disease. The proposed diagnostic criteria of FUO are imprecise and arbitrary at best, and the evaluation methods applied to every patient to reach the diagnosis are not uniform. As seen in the article by Vanderschueren et al,¹ the cause was identified in a large number of cases, although extensive evaluation, which may have a different meaning from one physician to another and from one time to another, might have required more than 3 to 4 weeks after the onset of fever. One physician's final diagnosis based on late diagnosis could be another physician's final diagnosis based on early diagnosis. Similarly, one physician's "no diagnosis"—I presume the authors mean there is no disease—can be another physician's early, intermediate, or late diagnosis. I am surprised to read that in their series "no diagnosis" was labeled for more than one third of patients. I have little doubt that the cause of FUO would be identified in most cases if a thoughtful physician uses his or her knowledge and skills and exercises patience. For instance, for physicians who are insightful with patience and dedication, even factitious fever can be uncovered.³ Besides, if we apply the term FUO to patients with factitious fever due to manipulation of thermometers,⁴ we might fall into a dangerous trap of deception and will deprive these patients of the care they need.