Psychological Medicine

Research Article

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

G. LIU a1 , M. R. CLARK a1 and W. W. EATON a1
a1 Department of Biostatistics, Department of Psychiatry and Behavioral Sciences and Department of Mental Hygiene, Johns Hopkins Hospital, Baltimore, MD, USA


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.


Address for correspondence: Dr Michael R. Clark, Department of Psychiatry and Behavioral Sciences, Johns Hopkins Hospital, Osler 320, 600 N. Wolfe Street, Baltimore, MD 21287-5371, USA.