A hierarchical classes analysis (HICLAS) of primary care patients with medically unexplained somatic symptoms.

This study used a clustering model, Hierarchical Classes Analysis (HICLAS), to examine patient groupings in a multiethnic sample of 1456 patients using primary care services at a university-affiliated community clinic in southern California. Somatic symptoms, psychiatric diagnoses and disability were studied using a survey instrument that included portions of the Composite International Diagnostic Interview (CIDI), the Diagnostic Interview Schedule (DIS) and the RAND-MOS Short Form Health Survey's (SF-36) 'physical functioning' dimension. HICLAS identified 11 clusters of patients with distinct patterns of medically unexplained somatic symptoms. These patient clusters varied with respect to psychiatric diagnoses and symptoms, gender, immigration status and disability. Results of this study suggest that the type of presenting symptom(s) and their various combinations may have diagnostic and prognostic value in primary care settings. These new findings may lead to further refinement of current diagnostic constructs for somatizing syndromes.