How many functional somatic syndromes?

OBJECTIVE: Patients with medically unexplained symptoms are given diagnoses dependent upon the particular medical specialty consulted--irritable bowel syndrome in gastroenterology, fibromyalgia in rheumatology and others. The purpose of this paper is to establish whether these 13 different syndromes are discrete entities.

METHODS: Consecutive new patients in seven outpatient clinics at two general hospitals were recruited. Patients completed questionnaires measuring symptoms and demographic data. Case notes were reviewed to ascertain whether the presenting symptoms were medically explained 3 months after the initial visit.

RESULTS: Complete data were available for 550 subjects. With 37 unexplained symptoms included in the model, 30% of the total variance could be explained by one factor using unrotated principal component analysis. When the 13 identified functional syndromes were included, it was evident that functional syndromes could not be assumed to be independent. A two-factor model was the best fit for the present data after rotation.

CONCLUSIONS: This study suggests that the existence of distinct functional somatic syndromes (FSSynd) as defined clinically in medicine should be reconsidered.