A cluster analysis-derived classification of psychological distress and illness behavior in the medically ill.

Background. The classification of psychological distress and illness behavior in the setting of medical disease is still controversial. Current psychiatric nosology does not seem to cover the spectrum of disturbances. The aim of this investigation was to assess whether the joint use of DSM-IV categories and the Diagnostic Criteria for Psychosomatic Research (DCPR), that provide identification of syndromes related to somatization, abnormal illness behavior, irritable mood, type A behavior, demoralization and alexithymia, could yield subtyping of psychosocial variables in the medically ill. Method. A cross-sectional assessment using both DSM-IV and the DCPR was conducted in eight medical centers in the Italian Health System. Data were submitted to cluster analysis. Participants were consecutive medical out-patients and in-patients for whom a psychiatric consultation was requested. A total of 1700 subjects met eligibility criteria and 1560 agreed to participate. Results. Three clusters were identified : non-specific psychological distress, irritability and affective disturbances with somatization. Conclusions. Two-step cluster analysis revealed clusters that were found to occur across clinical settings. The findings indicate the need of expanding clinical assessment in the medically ill to include the various manifestations of somatization, illness behavior and subclinical distress encompassed by the DCPR.