Abstract
Despite elevated rates of obsessive compulsive personality disorder (OCPD) in patients with obsessive compulsive disorder (OCD), no study has specifically examined comorbid OCPD as a predictor of exposure and ritual prevention (EX/RP) outcome. Participants were adult outpatients (n = 49) with primary OCD and a Yale-Brown Obsessive Compulsive Scale (YBOCS) total score ≥ 16 despite a therapeutic serotonin reuptake inhibitor dose for at least 12 weeks prior to entry. Participants received 17 sessions of EX/RP over 8 weeks. OCD severity was assessed with the YBOCS pre- and post-treatment by independent evaluators. At baseline, 34.7% of the OCD sample met criteria for comorbid DSM-IV OCPD, assessed by structured interview. OCPD was tested as a predictor of outcome both as a diagnostic category and as a dimensional score (severity) based on the total number of OCPD symptoms coded as present and clinically significant at baseline. Both OCPD diagnosis and greater OCPD severity predicted worse EX/RP outcome, controlling for baseline OCD severity, Axis I and II comorbidity, prior treatment, quality of life, and gender. When the individual OCPD criteria were tested separately, only perfectionism predicted worse treatment outcome, over and above the previously mentioned covariates. These findings highlight the importance of assessing OCPD and suggest a need to directly address OCPD-related traits, especially perfectionism, in the context of EX/RP to minimize their interference in outcome.