Method: In the PIONEER-IBS randomized controlled trial (RCT), participants initially completed symptom diaries daily for 7 weeks. Based on individual symptom patterns, eye movement desensitization and reprocessing (EMDR) or gut-directed hypnotherapy (GDH) were assigned in a personalized or a reverse personalized manner; a control group received optimized treatment as usual (TAU). The primary outcome was the feasibility of the study protocol. Secondary outcomes included changes in gastrointestinal and psychosocial measures after the interventions (T2) and at a three-month follow-up (T3).

Results: Of the 79 randomized patients, 58 (73.4%) completed their assigned intervention with at least 5/7 sessions. Baseline symptom burden was high (IBS-SSS at baseline: 314.19, STD ± 81.21). No significant differences in secondary outcomes were observed between personalized and reverse-personalized therapy at T2 and T3. Pre–post change scores within randomization groups revealed an improvement in somatic symptom burden in both intervention groups (SSS-8: p = 0.0027 personalized therapy; p = 0.05 reverse-personalized therapy) at T2.

Conclusion: In this study, novel concepts of personalizing therapy were demonstrated. However, the benefit of treatment allocation based on individual symptom dynamics, the validity of personalization approaches and the efficacy of EMDR in specific IBS subgroups represent distinct but intertwined questions that require further evaluation.

Highlights:

• Daily diary data collected over 7 weeks were analyzed using VAR analysis to assess individual symptom dynamics.
• Assigning treatment regimens based on dynamics between somatic and psychological symptoms is feasible.
• EMDR therapy is feasible and accepted by IBS patients.”