One-year follow-up of patients with cluster C personality disorders: a prospective study comparing patients with "pure" and comorbid conditions within cluster C, and "pure" C with "pure" cluster A or B conditions.

This one-year, post-treatment prospective study of consecutively admitted patients to a national psychiatric in-patient clinic, compares patients belonging to four subgroups of DSM-III-R personality disorder (PDs): "pure cluster A (N = 21), "pure" B (N = 67), "pure" C (N = 251), and Axis II "comorbid" C (N = 138). Outcome was measured by SCl-90 and occupational status. Axis I disorders were controlled for in all analyses. Contrary to our hypothesis, patients in pure cluster C had no better outcome than either Axis II comorbid cluster C patients or patients with pure cluster A or B. Although pure C patients relapsed in symptom distress after discharge, comorbid C patients did not. C patients with an additional Histrionic PD were less at risk to be a case at follow up (GSI level > 1.00). Cluster C disorders as a whole had negative impact upon outcome in the total sample. These findings suggest the need for better treatment of patients with cluster C conditions.