This study aims at testing the effect and feasibility of a new treatment strategy - hypnotherapy mediated with audio files - for children and adolescents with disorders of gut-brain-interaction (DGBI) in Sweden. The treatment protocol has been used and studied in Netherlands, but the investigators have translated and formed it to suit the Swedish population. This study is a feasibility study that is followed by a large RCT to compare different psychological treatment options for this patient group.

If hypnotherapy mediated via audio files proves to be effective and feasible for this patient group, it would mean:

1. An exponential increase in the availability of evidence-based treatments. The hypnotherapy treatment is markedly easier to distribute than e.g. cognitive behavior therapy (CBT) which requires chat contact with a psychologist and is made available regardless of where in Sweden the family lives. In addition to shortened waiting times for patients, this would decrease the pressure in somatic care.
2. Possibility to offer tailored treatments. No treatment works for everyone. It is reasonable to assume that treatments with such different focuses as hypnotherapy and exposure-based CBT may be differently effective for different patients. A new treatment option can help a larger proportion of patients.
3. A more cost-effective treatment. Gut-directed hypnotherapy with audio files is a very inexpensive treatment, which would likely result in significant cost savings for this patient population.

Hypnotherapy has shown promising results in international studies for treatment of DGBI. Gut-directed hypnotherapy for children is based on relaxation and imagery and sensation exercises with a focus on gastrointestinal symptoms ("directed daydreams", which both divert and provide a pleasant feeling in the body, which the child can use when the symptoms come). The aim is to both improve awareness of and increase control over the symptoms. Hypnotherapy is a safe treatment that has been shown to have minimal side effects. The research group in the Netherlands with whom investigators collaborate in this project has shown a significantly better effect in short and long term with hypnotherapy than with conventional medical treatment for children and adolescents with DGBI. Hypnotherapy via home-based self-exercises with audio files is proven as effective as individual therapy performed face-to-face by a therapist.

Preliminary results/ backround work: Collaboration with the Dutch group started, the treatment manual for gut-directed hypnotherapy has been translated into Swedish and has undergone cultural validation by experienced child psychologists and has been recorded in audiobook quality. The study website (where the families have access to the treatments and measure the outcomes) has been created. Comprehensive patient information material has been created about DGBI and hypnotherapy, which consists of both texts, films, and audio to reach all patient types (Fig 1a-b). The pilot study is ongoing since Sep 2023.

Aim: To test the practical aspects concerning patient recruitment, information about treatment, the treatment itself, measurement of outcome, required power for the main outcome. The lessons learned will help investigators to fine-tune the protocol and give the planned large RCT optimal conditions.

Study population: 30 patients (8-17 years, of which approximately half are 13-17 years) from Sachsska Children's Hospital's Gastrointestinal Clinic and Pediatric and Adolescent Medical Clinics in Stockholm, who are diagnosed with DGBI following Rome IV criteria. Before inclusion, the families meet with a study physician and a study nurse for an assessment of inclusion and exclusion criteria, for information about the study, and review of treatment principles.

Exposure: Gut-directed hypnotherapy exercises 5 times/week, for 12 weeks, delivered via audio files on the study's website (files can also be downloaded to mobile phone).

Outcome: At the beginning and end of the treatment and every third week during the treatment, the patients and parents will fill in self-assessments in the form of internationally validated questionnaires for symptom severity, quality of life, school absence etc, via an internet platform with identification control (which we have worked with in many previous projects). Improvement by >30% on the primary outcome measure is defined as clinically significant, based on international recommendations.

Power: In several previous pilot studies, 30 patients have been sufficient to obtain meaningfully tight confidence intervals for the outcome measures and to be able to conclude for future RCTs. However, no formal power analysis is relevant without a comparison group.

Inclusion Criteria:

• Diagnosis: irritable bowel syndrome, functional abdominal pain, functional dyspepsia (following the Rome IV diagnostic criteria)
• The participant and at least one of the parents must understand Swedish

Exclusion Criteria:

• other medical condition that better explains the symtoms
• Absence from school >40% and/or psychiatric diagnosis that is judged to be more primary than the gastrointestinal problems, in these cases the children/young people are judged to need more intensive and multi-professional treatment