EngageTEXT: Using phenotypes to enhance engagement with a diabetes text messaging intervention - Project Summary: Uncontrolled type 2 diabetes (T2D) poses a significant health challenge causing rise in morbidity and mortality in the US, especially impacting minoritized populations, who endure disproportionately higher rates of health complications. Behavioral health intervention leveraging low-cost, ubiquitous digital technology (e.g., mobile phones and text messages) can capture and address the complex psychosocial (e.g., stress) and behavioral factors (e.g., adherence to self-care) that significantly impact glycemic control. Text- messaging interventions have shown promise in improving disease management among patients with T2D; however, they are hampered by low engagement and high attrition, especially among minoritized populations, limiting their efficacy. The goal of this Pathway to Independence Award (K99/R00) is to accelerate the candidate’s transition to an independent investigator on digital health behavioral interventions (DHBI) with specific expertise in optimizing user engagement for improved health outcomes. In the K99 phase of this award, the candidate will leverage data from the recently completed i-Matter and newly renewed i-Matter2 trials (in formative phase), two AHRQ-funded text messaging DHBI for T2D patients to: 1) enhance his machine learning (ML) experience with additional training for developing phenotypes of individual’s engagement behavior, 2) obtain expertise in mixed- method designs and user-centered approaches for robust evaluation of the engagement phenotypes, and 3) obtain training in causal inference approaches for evaluating when and how engagement with DHBI becomes effective for intended T2D health outcomes. The candidate will recruit individuals who completed i-Matter for a survey (n=114) and purposefully sample 12 of them from the i-Matter2 formative phase for qualitative interviews. Using a mixed-method approach, the survey and interviews will gather insights into participants’ engagement with the DHBI, complementing their objective system use data, and will be used to evaluate their engagement phenotypes. In the R00 phase, the candidate will use acquired skills and training to develop a text-messaging intervention tailored to individual’s engagement phenotypes and test the efficacy of the tailored intervention against a non-tailored group (control) receiving standard text messages in a pilot randomized two-arm clinical trial (n=96). Following baseline assessments of demographics, health literacy, digital literacy, and adherence to T2D self-care behaviors, participants in both arms will receive text messages with questions related to T2D self- care for 9 months. Both groups will also participate in 3-, 6-, and 9-mo study visits when adherence to self-care behavior will be measured with a validated scale via REDCap surveys. The primary aim of this trial is to evaluate the efficacy of the tailored intervention on HbA1c reduction (primary outcome), and improved adherence to self- care behaviors (secondary outcome). Both groups will also be invited to participate in a post-study engagement survey which will be used to explore potential mechanisms that influence engagement’s effect on the clinical and behavioral outcomes (exploratory aim).