Individualized cognitive behavioral therapy for chronic pain in Japan: study protocol for a multicenter randomized...

Chronic pain imposes a substantial burden on individuals and society. Cognitive behavioral therapy for chronic pain (CBT-CP) has proven effective internationally, but randomized evidence in Japan is scarce. The first Japanese trial was a single-center, 16-session videoconference program that prioritized pain intensity. In contrast, this multicenter trial tests a brief, face-to-face, individualized CBT-CP program with quality of life (QoL) as the primary outcome.

This open-label, randomized, parallel-group superiority trial enrolls 60 adults aged 20-80 years with chronic pain persisting ≥ 3 months and EQ-5D-5L scores ≤ 0.80, indicating reduced QoL. Participants are randomized 1:1 to treatment as usual (TAU) plus an eight-session CBT-CP program or to a waitlist control receiving TAU only. The manualized intervention includes psycho-education, relaxation, activity pacing, and cognitive restructuring, delivered weekly face-to-face, with the goal of completing eight sessions within 14 weeks. If necessary, sessions may extend beyond the 15th week; however, the post-assessment is always conducted at 15 ± 2 weeks irrespective of intervention timing. Therapists meet prespecified eligibility criteria and receive structured training, supervision, and fidelity monitoring. The primary outcome is QoL (EQ-5D-5L) at 15 ± 2 weeks. Secondary outcomes include pain intensity, disability, depressive symptoms, catastrophizing, fear of movement, pain self-efficacy, and health-related QoL assessed by the SF-12. These outcomes, together with prognostic risk and somatic symptom burden, will also be examined as potential mediators or moderators. The intervention group undergoes a 27 ± 2-week follow-up to explore mid-term durability in a single-arm pre/post analysis. Analyses follow the intent-to-treat principle using linear mixed models, with effect sizes and confidence intervals reported; multiplicity will be considered in interpreting secondary outcomes. Blinding of participants and therapists is not feasible.

This trial will clarify the added value of a brief, fidelity-assured, face-to-face CBT-CP program in Japan, where implementation remains limited. Findings are expected to guide clinical adoption, workforce training, and dissemination, while also generating hypotheses about for whom and through which processes CBT-CP may confer benefit.

University Hospital Medical Information Network Clinical Trials Registry, UMIN000042798. Registered on 21 December 2020, https://center6.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000048858 .