The Frequency of the Chronic Fatigue Syndrome in Patients with Symptoms of Persistent Fatigue

Abstract

A cohort study was made of 135 patients to determine the frequency of the chronic fatigue syndrome among patients with symptoms of 6 months or more. All patients had a complete history taken, had a physical examination and a comprehensive battery of blood test, and were given the Diagnostic Interview Schedule of the National Institute of Mental Heath, a highly-structured 260-item instrument designed to enable accurate psychiatric diagnoses. Other diagnostic studies (for example, sleep studies and electroencephalography) were ordered if necessary for individual patients. Six of the one hundred thirty-five patients met criteria for chronic fatigue syndrome (95% CI, 0 to 10). Ninety-one (67%) patients (CI, 56 to 78) had clinically active psychiatric disorders and 4 (3%) patients (CI, 0 to 8) had medical disorders that were considered a major cause of their fatigue. Thirty-four (25%) patients (CI, 14 to 36) had insufficient symptoms or objective findings of the chronic fatigue syndrome. It was concluded that the chronic fatigue syndrome is rare among patients with symptoms of persistent fatigue. Most of these patients have psychiatric disorders.