Introduction
Irritable bowel syndrome (IBS) is the most common disorder of gut-brain interaction with a worldwide prevalence of approx. 11%. Gut-directed hypnotherapy (GDH) is an effective IBS-targeted therapy, but with limited accessibility. Nerva is an app-delivered GDH program aimed to improve access, but efficacy data is limited to a retrospective study, showing improved gastrointestinal and psychological outcomes. Controlled-trial evidence for Nerva is warranted.

Aim
To compare app-delivered GDH program Nerva (GDH and psychoeducation) to psychoeducation alone on gastrointestinal symptoms and psychological outcomes in IBS.

Methods
Participants with self-reported IBS according to Rome IV criteria were recruited from Australia and the USA and randomised to receive Nerva (GDH and psychoeducation) or psychoeducation alone. Intervention delivery was via smartphone application for 42 sessions (6 weeks). Gastrointestinal symptoms were assessed by the IBS-SSS. Clinical response was defined as <50 IBS-SSS points at program completion. FDA recommended clinical improvement of >30% for abdominal pain was also considered. Psychological outcomes and QOL were scored using the depression anxiety and stress scale (DASS-21), symptoms checklist - 90 (SCL-90) and IBS-QOL. Outcomes were assessed at baseline and every 14 days until program completion.

Results
Of 244 enrolled participants, 45 withdrew prior to completing the first 14 sessions. 199 were included in a modified intention-to-treat analysis and 174 (87%) completed the 42-session program. There was no difference between groups on baseline demographics. Median age was 37 (IQR 30-46) years and 180 (91%) were female. There was an even distribution of participants from Australia and the USA. Baseline gastrointestinal symptoms, psychological scores and QOL were similar between the two groups. IBS-SSS was lower following Nerva compared to psychoeducation (Nerva 199.5 (131-303.5) vs psychoeducation 246 (165-308); p=0.032; Figure 1). Both interventions led to clinically relevant improvements in IBS-SSS scores (Nerva (97; IQR 41-166) vs psychoeducation (57; 0-123); p=0.008). GDH induced clinical response in 71% compared to 53% with psychoeducation (p=0.011; chi-square) and there was a divergence in symptom improvement from 28 sessions (Figure 1). Both interventions led to >30% improvement in pain (Nerva 59% vs psychoeducation 41%; p=0.009). Both interventions significantly improved DASS-21, SCL-90 and IBS-QOL scores equally (Table 1).

Discussion
App-delivered GDH program, Nerva, is superior to psychoeducation in terms of improving IBS symptoms to a lower level and in a greater percent of participants. It is also effective in improving psychological outcomes and patient QOL. These results support wide-spread use of app-delivered GDH for IBS sufferers, that is cheaper and more accessible that in-person therapy.

Ellen Anderson

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