THE VALIDITY AND RELIABILITY OF THE FATIGUE SYNDROME THAT FOLLOWS GLANDULAR FEVER

The validity and reliability of an empirically defined fatigue syndrom e were tested in a prospective cohort study of 245 primary care patien ts, with glandular fever or an upper respiratory tract infection. Subj ects were interviewed three times in the 6 months after onset. Subject s with the empirically defined fatigue syndrome were compared with tho se who were well and those who had a psychiatric disorder. The validit y of the fatigue syndrome was supported, separate from psychiatric dis orders in general and depressive disorders in particular. Only 16% of subjects with the principal component derived fatigue factor also met criteria for a psychiatric disorder (excluding pre-morbid phobias). Co mpared with subjects with psychiatric disorders, subjects with the ope rationally defined fatigue syndrome reported more severe physical fati gue, especially after exertion, were just as socially incapacitated, h ad fewer mental state abnormalities, and showed little overlap on inde pendent questionnaires. A more mild fatigue state also existed. Both t he fatigue syndrome and state were more reliable diagnoses over time t han depressive disorders. The empirically defined fatigue syndrome pro bably is a valid and reliable condition in the 6 months following glan dular fever.