Chiaki NAKAYAMA

Importance Cognitive processing therapy (CPT) is an evidence-based treatment for posttraumatic stress disorder (PTSD). However, there is little evidence on the efficacy of CPT in East Asia. Objective To evaluate whether CPT is effective in treating PTSD among outpatients in a Japanese medical setting. Design, Setting, and Participants This randomized clinical trial used a 16-week, single-center, assessor-blinded, parallel-group superiority design to examine the efficacy of CPT in conjunction with treatment as usual (CPT-TAU) vs waiting list with TAU (WL-TAU) from April 2016 through December 2022. The trial included adult patients with PTSD at a national psychiatric referral hospital in Tokyo, Japan. Analysis was based on intention to treat and per protocol and was performed from February 1 to April 30, 2024. Interventions Participants were randomized 1:1 to CPT-TAU (n = 29), which consisted of 12 weekly individual CPT sessions, or WL-TAU (n = 31), which consisted of clinical monitoring and/or pharmacotherapy. Main Outcomes and Measures The primary outcome was the Clinician-Administered PTSD Scale (CAPS-5) score for the Diagnostic and Statistical Manual of Mental Disorders (Fifth Edition) at 17 weeks. Secondary outcomes included self-reported PTSD symptoms assessed by the PTSD Checklist–5 and responder status at 17 weeks. Adverse events were evaluated using the Japanese version of the Common Terminology Criteria for Adverse Events, version 4.0. Results Among 60 eligible participants (all included in the intention-to-treat analysis), mean (SD) age was 36.9 (9.9) years; 54 (90.0%) were women. The CPT-TAU group showed a mean (SE) reduction in CAPS-5 scores of 14.00 (1.92) points, with a low dropout rate (2 of 29 [6.9%]). Patients in the CPT-TAU group showed superiority in all secondary and other outcomes. The mean change difference was observed in depression (8.83; 95% CI, 6.00-11.66), suicidal ideation (6.73; 95% CI, 1.25-12.22), disability (8.16; 95% CI, 3.90-12.43), clinical global impression (0.84; 95% CI, 0.41-1.26), and loss of principal PTSD diagnosis (59.09; 95% CI, 37.19-81.00). There were no serious adverse events in the CPT-TAU group and 3 serious adverse events in the WL-TAU group during the intervention period. Conclusions and Relevance In this randomized clinical trial of CPT-TAU vs WL-TAU, CPT was superior in reducing PTSD symptoms. These results strengthen the evidence for use of CPT in East Asian populations. Trial Registration Umin.Uc.Jp/Ctr Identifier: UMIN000021670