Engaging diverse colorectal cancer survivors in the design of an adaptive text message-based intervention to improve diet quality

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Colorectal cancer (CRC) is the 2nd leading cause of cancer death in the United States. Interventions that are accessible and effective in the large, culturally diverse populations of people affected by CRC will greatly improve public health. Dietary interventions hold particular promise for reducing CRC mortality because strong evidence supports that a high-fiber diet rich in whole grains is associated with lower mortality among people with CRC. Yet, <15% of CRC survivors consume a high-fiber diet. Therefore, our goal is to develop a scalable intervention to increase intake of whole grains and reduce intake of refined grains that is acceptable to CRC survivors of varied cultural backgrounds. Text messages are a promising intervention component for reaching a wide range of CRC survivors. However, most studies have developed and tested “one size fits all” static programs with limited generalizability. To address this gap, we propose to develop a continuously adaptive text message-based intervention using reinforcement learning (RL). RL is a type of machine learning that can be used to optimize text messages over time based on participant characteristics (e.g., race/ethnicity, language), engagement, and/or behavior. Dr. Aguilera (co-I) has developed a text message intervention that uses RL to increase physical activity in low income people with depression and diabetes; messages are sent in English or Spanish. While promising, it is not known if a RL algorithm can be used to improve diet behavior. In this proposal, we will develop a RL algorithm to optimize text message content and timing based on whole grain intake assessed through text messages. Informed by the Capability Opportunity Motivation – Behavior (COM- B) model, we propose an embedded mixed method study. In Aim 1, we will conduct four focus groups among Black, Latinx, non-Latinx white, and Asian American/Pacific Islander CRC survivors (5-8/group) and 20 semi- structured interviews. We aim to understand CRC survivors’ capabilities, opportunities, and motivations for a healthy diet and preferences for text messages. Using these data, we will refine our theoretical framework and revise/update our library of >200 diet-focused text messages from previous work in non-Latinx white cancer survivors. In Aim 2, informed by Aim 1, we will develop an adaptive text message intervention using RL to increase the proportion of grains consumed that are whole grains among CRC survivors. We will determine the intervention’s feasibility and acceptability and estimate its effect on diet (intake of whole grains, refined grains, total fiber) in a 12-week single-arm study among 60 CRC survivors, approximately equal numbers of whom identify as Black, Latinx, non-Latinx white, and Asian American/Pacific Islander. Our multidisciplinary and multicultural team has the expertise needed to complete this study. Our proposal will inform a scalable dietary intervention with broad generalizability that we will ultimately test in a randomized controlled trial. Improving CRC survivors’ diet quality has potential to reduce CRC mortality and have great public health impact.