In a recent study published in a special issue of the Journal: Cognitive Therapy and Research metacogniitve therapy was compared with exposure therapy and a control condition in the treatment of post-traumatic stress disorder. MCT produced effects more rapidly then exposure and was more effective at the end of treatment. At follow-up MCT showed maintenance of gains but at that point the exposure group had caught up.
Reference: Wells, A. Walton, D., Lovell, K. & Proctor, D. (2015). Metacognitive therapy versus prolonged exposure in adults with chronic post-traumatic stress disorder: A parallel randomized controlled trial. Cognitive Therapy and Research, 39, 70-80.