Remote Self-help cognitive-behavioural Therapy for irritable bowel syndrome (ReSeT): protocol for a randomised controlled trial

Irritable bowel syndrome (IBS) may significantly impair the quality of life (QoL) of affected individuals and carries substantial socio-economic consequences. Cognitive-behavioural therapy (CBT) is recommended as one treatment option for IBS. However, its widespread use is limited by a shortage of qualified therapists, insufficient facilities, and the burden of hospital visits. Internet-based CBT (iCBT) has the potential to overcome these challenges. We aim to evaluate the efficacy and cost-effectiveness of iCBT for treating drug-refractory IBS through rigorous methodology. This is a single-blind, multicentre, randomised controlled trial. We will recruit adults (≥ 18 years) with moderate-to-severe drug-refractory IBS (target sample size: 132, allowing for an estimated 20% attrition) and randomise them 1:1, stratified by baseline IBS severity. The intervention arm will receive iCBT with interoceptive exposure (iCBT-IE), including brief therapist videoconferences, while the control arm will receive IBS disease education and lifestyle advice. Both arms will undertake 10-week internet-based programmes in addition to continuing treatment as usual. The primary outcomes will be changes in IBS severity (IBS-SSS) and IBS-specific QoL (IBS-QOL) from baseline to week 13, with long-term effects assessed up to week 52. IBS-SSS (range: 0–500) decreases with improvement, whereas IBS-QOL (range: 0–100) increases with improvement. Analyses will follow the intention-to-treat principle, using a mixed-effects model for repeated measures (MMRM). Cost-effectiveness will be assessed from the payer’s perspective using IBS-SSS, quality-adjusted life years (QALYs), and healthcare resource use. Productivity will be evaluated from a societal perspective using the Work Productivity and Activity Impairment Questionnaire: General Health (WPAI:GH). Telepsychotherapy, including iCBT, is expected to expand because of its convenience. However, the efficacy and cost-effectiveness of non-verbal therapists interventions in telepsychotherapy have not been adequately evaluated. Evaluating iCBT with videoconferencing guidance is therefore crucial to broaden treatment options for IBS. Registered on 1 November 2023 in the UMIN-CTR (https://www.umin.ac.jp/ctr/index-j.htm), ID: UMIN000052457. This is the first version of the protocol.