Structural factor analyses for medically unexplained somatic symptoms of somatization disorder in the Epidemiologic Catchment Area Study

Background. Assess the latent structure of the DSM-III somatization symptoms and the stability of symptom patterns over time. Methods. Cross-sectional and longitudinal covariation of symptoms of somatization disorder were investigated using structural equation models in a population-based data set from the Epidemiologic Catchment Area study. Results. Medically unexplained physical complaints were discovered to cluster into three separate factors, consistent with the DSM-IV definition of somatization disorder, but one dominant general factor was defined, consistent with the DSM-III conceptualization. Individual symptom prevalences and factor structures were different for men and women. The factor structures remained stable at 1 year follow-up. Variations in the threshold of number of somatization symptoms required for diagnosis affected prevalence, sex ratio and temporal stability of the diagnosis. Conclusions. These population-based results support dimensional models of somatization. Implications for changing the threshold of the categorical diagnosis of somatization disorder and providing better care for these patients are given.