Akiko Kikuchi

Cognitive processing therapy (CPT) is one of the most widely tested evidence-based treatments for posttraumatic stress disorder (PTSD). However, most studies on CPT have been conducted in Western cultural settings. This open-label, single-arm trial investigated the feasibility, acceptability, and preliminary efficacy of CPT for treating Japanese patients with PTSD. A total of 25 outpatients underwent 12 CPT sessions. The primary outcome was the assessment of PTSD symptoms using the Clinician-Administered PTSD Scale for DSM-IV (CAPS-IV); secondary outcomes included the assessment of subjective PTSD severity, depressive and anxiety symptoms, trauma-related cognitions, and subjective quality of life. All outcomes were evaluated at pretreatment (i.e., baseline), posttreatment, and 6- and 12-month follow-ups. On average, participants attended 13 sessions of CPT (SD = 1.38), with a completion rate of 96.0%. One serious adverse event (hospitalization) occurred. Significant within-subjects standardized mean differences in CAPS-IV scores were found from baseline to treatment completion, g = -2.28, 95% CI [-3.00, -1.56]; 6-month follow-up, g = -2.95, 95% CI [-3.79, -2.12]; and 12-month follow-up, g = -2.15, 95% CI [-2.89, -1.41]. Moderate-to-large effects, gs = -0.77 to -2.45, were found on secondary outcomes. These findings support the feasibility, acceptability, and preliminary efficacy of CPT in a Japanese clinical setting.