GutCheck: Optimization of a Personalized Mobile Health App for Survivors of Gastrointestinal Cancer

There are two components to the study: a patient and a clinician study. The clinician study will include one-hour semi-structured interviews with oncology specialists to identify facilitators and barriers to integrating digital diet interventions into the clinical workflow, and to understand their needs and preferences for digital diet interventions. The patient study aims to investigate initial feasibility, efficacy and acceptability of the GutCheck app and intervention. It will last 9 weeks and involves 2 study visits and 2 active phases with a transition week and optional transition visit between phases. During active phases, participants will be asked to use the GutCheck app every day. Prior to the first active phase, participants will go through informed consent and app training. The first active phase will last two weeks and will focus on tracking participants' diet, gastrointestinal (GI) symptoms, and stress. The data collected during the first active phase will be used to identify any potential trigger foods that may contribute to GI symptoms, but only if the participant reports experiencing GI symptoms. Between active phases, participants will have one Transition Week, where results from the first phase are given to the participants with the option to attend a Transition Week Visit. The second active phase will last four weeks and will involve the message intervention. A single-blind, micro-randomized trial design will be used to repeatedly randomize participants to different intervention combinations, determining both the timing and frequency of intervention message delivery throughout the day. Lastly, there will be an exit visit and interview within a week from the intervention to collect post-intervention measures and ask about the participant's experience with the GutCheck app.