A two-year follow-up study of chronic fatigue syndrome comorbid with psychiatric disorders.

AIMS: Chronic fatigue syndrome patients often have comorbid psychiatric disorders such as major depressive disorders and anxiety disorders. However, the outcomes of chronic fatigue syndrome and the comorbid psychiatric disorders and the interactions between them are unknown. Therefore, a two-year prospective follow-up study was carried out on chronic fatigue syndrome patients with comorbid psychiatric disorders.
METHODS: A total of 155 patients who met the Japanese case definition of chronic fatigue syndrome were enrolled in this study. Comorbid psychiatric disorders were diagnosed according to the Diagnostic and Statistical Manual of Mental Disorders 4th edition criteria. Patients with comorbid psychiatric disorders received psychiatric treatment in addition to medical therapy for chronic fatigue syndrome. Seventy patients participated in a follow-up interview approximately 24 months later.
RESULTS: Of the 70 patients with chronic fatigue syndrome, 33 patients were diagnosed as having comorbid psychiatric disorders including 18 major depressive disorders. Sixteen patients with psychiatric disorders and eight patients with major depressive disorders did not fulfill the criteria of any psychiatric disorders at the follow up. As for chronic fatigue syndrome, nine out of the 70 patients had recovered at the follow up. There is no significant influence of comorbid psychiatric disorders on the outcome of chronic fatigue syndrome.
CONCLUSIONS: Chronic fatigue syndrome patients have a relatively high prevalence of comorbid psychiatric disorders, especially major depressive disorders. The outcomes of chronic fatigue syndrome and psychiatric disorders are independent. Therefore treatment of comorbid psychiatric disorders is necessary in addition to the medical treatment given for chronic fatigue syndrome.