Smartphone app prototype for irritable bowel syndrome therapy passes first usability test

A three-month study in Japan has shown that adults with irritable bowel syndrome will faithfully log their symptoms on a smartphone every day, even when the technology is nothing more glamorous than a stack of Google Forms. Ten patients completed the entire study period, and their mean daily diary completion rate reached 94.9 percent, with individual rates ranging from 79.4 to 100 percent. The findings, published in BioPsychoSocial Medicine, offer an early signal that a planned mobile application delivering cognitive behavioral therapy could win the sustained engagement that digital health tools so often fail to secure.

The research team, led by investigators from The University of Tokyo, Tohoku University, and collaborating institutions, set out to test the building blocks of a future Just-in-Time Adaptive Intervention, or JITAI, for IBS. Cognitive behavioral therapy has repeatedly been shown in trials and meta-analyses to ease IBS symptoms and abdominal pain, yet its reach is constrained by a shortage of clinicians trained in the technique and by the heavy time demands it places on both patients and therapists. A JITAI framework uses smartphones, sensors, and analytics to detect the moments when a patient most needs support, and the researchers wanted to know whether the core functions of such a system could work in daily life before investing in full application development.

Because building software is slow and expensive, the team simulated the intended application with Google Forms and email. Participants received a scheduled email prompt each day containing a link to a symptom diary that took only a few minutes to complete, capturing abdominal pain intensity and frequency, triggers, coping strategies, physical status, and mood. Entries flowed automatically into a secure central database that physicians could review on a computer or tablet and discuss during routine clinic visits. The study was conducted at three psychosomatic outpatient clinics: The University of Tokyo Hospital, Tohoku University Hospital, and Tohoku Rosai Hospital, with enrollment periods running from May through December 2022.

The exposure component drew on systematic desensitization, a technique in which patients gradually confront feared situations while their anxiety declines. At an initial visit, each participant and a physician built a personalized anxiety hierarchy listing IBS-related scenarios, such as traveling far from a restroom, ranked from least to most distressing using Subjective Units of Distress, or SUD scores. Whenever a participant carried out an exposure exercise in real life, they logged it immediately and rated their anxiety before and after. If a reported SUD fell below 30 for a chosen scenario, the system emailed a suggestion to consider moving to a harder step, an automation intended to mimic the adaptive prompting of a true JITAI. Four board-certified psychosomatic physicians, all with formal CBT training, provided the exposure-based support alongside routine care.

Participants also received access to an educational website covering the basics of IBS and the rationale for exposure therapy, guided by Japan’s 2020 evidence-based clinical practice guidelines for the condition. The site emphasized structured lifestyle habits, moderate exercise, proper diet, symptom reframing, and stress management, and explained how to construct an anxiety hierarchy. On average, participants recorded 17.2 exposure sessions over the three months, though the range was strikingly wide, from 2 to 53 sessions. Across the cohort, the maximum SUD level of any exposure scenario attempted ranged from 70 to 100, indicating that several patients worked their way up to the most distressing items on their personal lists.

The ten participants, seven men and three women with a mean age of 28.4 years, all met Rome IV criteria for IBS. Six had IBS with diarrhea, three had IBS with both constipation and diarrhea, and one had unclassified IBS; notably, no patients with IBS with constipation were enrolled. All ten finished the study. Eight completed the final usability questionnaire, which the study team developed specifically for this prototype and rated on five-point Likert scales. Six of the eight respondents, or 75 percent, agreed or strongly agreed that they wanted to continue the daily symptom diary, and five of eight, or 62.5 percent, said they would recommend the prototype to others with IBS symptoms. No respondent selected disagree on either item.

Not every component performed equally well. Ease-of-use ratings were split for the diary, with three of eight participants rating it easy or very easy and an equal number calling it difficult or very difficult. Creating the anxiety hierarchy drew mixed reviews, with two of eight rating it difficult, while exposure logging fared better, with seven of eight finding it neutral or easy. The educational website was the clear weak point: six of eight respondents reported using it not much or not at all, and interviews confirmed that only one of three interviewed participants had viewed it. Ironically, the content itself was not blamed, since no respondent rated the information as unhelpful and one called it helpful or very helpful, suggesting the problem lay in delivery rather than substance.

Semi-structured interviews added texture to the numbers. All three interviewed patients said routine logging increased their awareness of symptom patterns or triggers. Two participants who repeatedly practiced exposure reported completing the highest-level scenario on their hierarchy, with a SUD score of 100, and perceived that their distress declined with repeated practice, an experience that encouraged them to keep going. Physician interviews, conducted with four investigators, highlighted a different set of priorities: two physicians called for a more integrated mobile interface that would streamline hierarchy creation and provide clearer, real-time visual feedback within the clinical workflow. These observations will directly shape the next development phase.

The authors are careful about what this study does and does not show. Because the trial focused on usability and feasibility, no formal clinical outcomes or symptom changes attributable to the intervention were assessed, and it remains unknown whether this approach improves IBS severity, anxiety, or quality of life. The sample of ten was chosen because prior usability research indicates that five participants can identify roughly 85 percent of usability issues and ten can detect about 98 percent, but such a small, male-predominant cohort limits generalizability, particularly given epidemiological evidence that IBS is more prevalent among women. The absence of any IBS-C patients leaves an entire subtype untested, and the Google Forms platform, while ideal for rapid prototyping, cannot replicate the convenience and engagement of a polished native application.

Even with those caveats, the adherence figures stand out. In a comparable nine-week web-based CBT program for IBS patients, delivered alongside usual care, adherence reached only 69 percent, defined as completing at least four of eight web-based sessions and at least one of three therapist support sessions, and non-adherence predicted missing primary outcomes at twelve months. Against that benchmark, a 94.9 percent mean diary completion rate sustained over three months is a noteworthy result. The researchers conclude that smartphone self-tracking and exposure exercises are acceptable to IBS patients, and that the future application should automate hierarchy building, embed educational content directly, and include participants with a broader range of IBS subtypes. Larger, controlled trials with a dedicated JITAI application remain the necessary next step to determine whether this engagement translates into genuine clinical benefit.

Subject of Research: A usability and feasibility study of a Google Forms prototype for a Just-in-Time Adaptive Intervention delivering cognitive behavioral therapy components to adults with irritable bowel syndrome in Japan.

Article Title: Usability study to guide the development of a cognitive behavioral therapy mobile application for reducing irritable bowel syndrome symptoms

Article References: Yamazaki, T., Kurisu, K., Machida, T., Kunio, M., Kanemitsu, Y., Hanadate, T., Fukudo, S., & Yoshiuchi, K. (2026). Usability study to guide the development of a cognitive behavioral therapy mobile application for reducing irritable bowel syndrome symptoms. BioPsychoSocial Medicine, 20(1), Article 8. https://doi.org/10.1186/s13030-026-00354-2

Image Credits: AI Generated

DOI: 10.1186/s13030-026-00354-2

Keywords: irritable bowel syndrome, cognitive behavioral therapy, mobile health, Just-in-Time Adaptive Intervention, exposure therapy, symptom diary, usability study, digital health, gut-brain interaction, self-monitoring, anxiety hierarchy, patient adherence