RIEKO KONNO

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.