Latent variable models of functional somatic distress.

Latent variable models of functional somatic symptoms were estimated for a sample of 686 family medicine patients. Symptom items from the NIMH Diagnostic Interview Schedule were selected to approximate diagnoses of fibromyalgia syndrome (FMS), chronic fatigue syndrome (CFS), and irritable bowel syndrome (IBS). Confirmatory factor analysis demonstrated that hypothesized latent variables of somatic depression, somatic anxiety, FM-like, CF-like, and IB-like syndromes fit the observed covariations better than models hypothesizing fewer latent variables. Results offer tentative confirmation of functional somatic syndromes as discrete entities and suggest that relaxing the diagnostic criteria for somatization may identify individuals with distress limited to a single functional system.