A randomized trial of fluoxetine in a patient with persistent fatigue.

Chronic fatigue syndrome is a disorder of unknown cause that is characterized by debilitating fatigue for at least 6 months. Formal criteria for the diagnosis of this syndrome were established in 1988 by the Centers for Disease Control (CDC).l Even though fatigue ranks among the most common problems in primary care,2 most persons afflicted with fatigue fail to satisfy the Centers for Disease Control criteria for chronic fatigue syndrome. In fact, in one study of 135 patients with persistent fatigue, only 6 met the criteria for chronic fatigue syndrome.3 "While the cause and treatment of chronic fatigue syndrome remain open to speculation, even less is known about patients with persistent fatigue who do not meet CDC criteria for chronic fatigue syndrome. Because many chronic fatigue syndrome patients and patients with persistent fatigue experience mood changes4 and major depression,s it has been speculated that chronic fatigue syndrome in some patients might result from neurochemical mechanisms similar to those observed in major depression.6 "While this mechanism might explain the cause of chronic fatigue syndrome in some patients, it is likely that there are also other causes of chronic fatigue syndrome, which would explain why none of a variety of pharmacological agents used thus far has been successful on the whole population of patients with persistent fatigue.7 Although treatment approaches are often established by randomized clinical trials, treatment decisions in chronic fatigue syndrome cannot be guided by such trials because they have not yet shown an effective treatment.s In addition, treatment decisions that are generalized from studies with different eligibility criteria might be unwarranted for a specific patient.