Mindfulness-based cognitive therapy (MBCT) in patients with obsessive-compulsive disorder (OCD) and residual symptoms after cognitive behavioral therapy (CBT): a randomized controlled trial.

Up to one-third of individuals with obsessive-compulsive disorder (OCD) do not benefit from evidence-based psychotherapy. We examined the efficacy of mindfulness-based cognitive therapy (MBCT) as a complementary treatment option. In a prospective, bicentric, assessor-blinded, randomized, and actively controlled clinical trial, 125 patients with OCD and residual symptoms after cognitive behavioral therapy (CBT) were randomized to either an MBCT group (n = 61) or to a psychoeducational group (OCD-EP; n = 64) as an active control condition. At post-treatment, there was no significant benefit of MBCT over OCD-EP with the Yale-Brown-Obsessive-Compulsive Scale (Y-BOCS) as the primary outcome measure, but with the Obsessive-Compulsive Inventory [OCI-R; F(1, 101) = 5.679, p = .036, effect size η ² _partial  = 0.053]. Moreover, the response rate and the improvement on secondary outcomes such as obsessive beliefs and quality of life was significantly larger in the MBCT group. Non-completion rates were below 10%. At the 6-month follow-up, OC symptoms were further improved in both groups; group differences were no longer significant. Our findings suggest that MBCT, compared to a psychoeducational program, leads to accelerated improvement of self-reported OC symptoms and secondary outcomes, but not of clinician-rated OC symptoms. In the midterm, both interventions yield similar and stable, but small improvements, suggesting that additional treatment options may be necessary.