Perfectionism and Treatment Outcome in Obsessive-compulsive Disorder

This study examined the relationship between perfectionism, as measured by the Multidimensional Perfectionism Scale (MPS; [R. O. Frost et al. (1990) Cognitive Therapy and Research, 14, 449–468], and treatment outcome in obsessive compulsive disorder (OCD). Patients (n = 118) participated in group [McLean et al. (2001) Journal of Consulting and Clinical Psychology, 69, 205–214] or individual [Whittal et al. (2005) Behaviour Research and Therapy, 43, 1559–1576] cognitive therapy (CT) or exposure and response prevention (ERP) for OCD. Doubts about Actions (DA), a subscale of the MPS, uniquely predicted worse treatment outcome in the Yale-Brown Obsessive-compulsive Scale (YBOCS; [Goodman et al. (1989) Archives of General Psychiatry, 40, 1006–1011]) total score and compulsions subscale. Interactions between Concern over Mistakes (CM; another MPS subscale) and DA, as well as DA alone, predicted poorer treatment outcome in patients who received ERP. Contrary to expectations, MPS total score was not related to treatment response. Moreover, levels of perfectionism did not change over the course of treatment, regardless of the type of treatment received. Implications for treatment in OCD are discussed.