The Somatoform Spectrum Within the Hierarchical Taxonomy of Psychopathology System: A Taxometric Test of the Latent Structure.

Abstract

The general understanding of disorders related to chronic somatic symptoms (e.g., somatic symptom disorder, functional somatic syndromes) is limited because of current categorical conceptualizations in traditional taxonomies. To improve clinical utility and validity, the Hierarchical Taxonomy of Psychopathology offers an empirically grounded dimensional approach. Therefore, the distribution of persistent somatic symptom distress observed in nature is highly relevant for informing decisions related to classification and treatment. This study analyzes the underlying structure of symptoms associated with the somatoform spectrum. Taxometric analyses were used to examine the latent status of the somatoform spectrum, which was measured via a dimensional questionnaire devised as part of the Hierarchical Taxonomy of Psychopathology scale development effort. We generated Comparison Curve Fit Index (CCFI) profile analyses across a clinical sample of psychotherapy outpatients ( n = 487), a community sample of German adults ( n = 451), and a student sample from New Zealand ( n = 549). In the clinical sample (CCFI mean = 0.38) and in the student sample (CCFI mean = 0.36), a dimensional solution was clearly favored. Results in the community sample (CCFI mean = 0.51) were ambiguous. Across the three independent samples, qualitatively distinct subgroups within the distribution of chronic somatic symptoms could not be identified. Therefore, continuous representations seemed to best represent the structure of somatic symptoms. Implications of these findings for etiology and treatment are discussed.