A 2019 meta-analysis of 11 studies with a total of 1130 participants showed that CPT outperformed inactive control conditions on PTSD outcome measures at posttreatment and follow-up.
The average CPT-treated participant fared better than 89% of those in inactive control conditions at posttreatment and 82% at follow-up.
Reference
Gordon J. G. Asmundson, Audur S. Thorisdottir, Jacob W. Roden-Foreman, Scarlett O. Baird, Sara M. Witcraft, Aliza T. Stein, Jasper A. J. Smits & Mark B Powers (2019) A meta-analytic review of cognitive processing therapy for adults with posttraumatic stress disorder, Cognitive Behaviour Therapy, 48:1, 1-14,DOI: 10.1080/16506073.2018.1522371