Influence of co-morbid generalized anxiety disorder, panic disorder and personality disorders on the outcome of cognitive behavioural treatment of obsessive-compulsive disorder.

This study examined co-morbid generalized anxiety disorder and/or panic disorder and personality disorders as predictors of treatment outcomes in adult outpatients with obsessive-compulsive disorder. The patients received exposure with response prevention (ERP) treatment with the addition of either elements of cognitive therapy (ERP+CT) or relaxation training (ERP+REL). It was hypothesized that the addition of cognitive interventions would yield better treatment outcomes for patients with co-morbid generalized anxiety disorder and/or panic disorder. It was also hypothesized that patients with any personality disorder would show less treatment gains in both conditions. Using intention-to-treat criteria, patients with generalized anxiety disorder and/or panic disorder co-morbidity showed less treatment gains at post-treatment across both treatment conditions. This group showed significantly more treatment gains in the ERP+CT condition at the post-treatment and the 12-month follow-up assessments compared with patients in the ERP+REL condition. However, this was not significant when comparing treatment completers. Patients with a co-morbid Cluster A or B personality disorder showed significantly less treatment gains in both treatment conditions at the 12-month follow-up assessment. Among treatment completers, patients with a Cluster C personality disorder showed significantly better outcomes at the post-treatment assessment in the ERP+REL treatment condition. These results, clinical implications, and the importance of further investigations are discussed.