Background. - Comorbid personality disorders (PDs) are discussed as risk factors for a negative treatment outcome in obsessive-compulsive disorder (OCD). However, studies published so far have produced conflicting results. The present study examined whether PDs affect treatment outcome in patients with OCD.

Method. - The treatment sample consisted of 55 patients with OCD who were consecutively referred to a Behaviour Therapy Unit for an in-patient or day-clinic treatment. Treatment consisted of an individualised and multimodal cognitive behaviour therapy (CBT, with or without antidepressive medication). Measurements were taken prior and after treatment and 6-month after admission.

Results. - A large percentage of patients benefited from treatment irrespective of the presence of a PD and were able to maintain their improvement at follow-up. Duration of treatment was not prolonged in OCD patients with concomitant Axis II disorders. However, some specific personality traits (schizotypal, passive-aggressive) were baseline determinants for later treatment failure at trend level.

Conclusions. - Results are encouraging for therapists working with patients co-diagnosed with Axis II disorders since these patients are not necessarily non-responders. The results stress the importance of a specifically tailored treatment approach based on an individual case formulation in OCD patients with complex symptomatology and comorbid Axis II disorders.