Sexual and gender minority (SGM) populations are disproportionately impacted by mental health concerns relative to their heterosexual and cisgender peers. Despite high need, SGM populations continue to report unmet mental health needs because they cannot or do not access mental health services. Digital Mental Health (DMH) services have been recognized as feasible, economical, and effective options to broaden the availability of mental health care to consumers who face barriers to mental health help-seeking. SGM consumers cite a preference for DMH care and this delivery format holds promise to attend to major mental health care access barriers experienced by this consumer group. Yet, the availability of DMH services tailored to the needs of SGM consumers is limited, and a dearth of research examines SGM populations' actual engagement with DMH services. A potential solution to fully understand how SGM populations utilize DMH services would be to characterize their engagement within a natural setting. Leveraging an established partnership with Mental Health America (MHA), a non-profit mental health advocacy group offering free, evidence-based screenings and self-guided DMH resources, this study will follow a large, naturalistic sample of SGM DMH consumers with the aim to test tailored engagement strategies with SGM DMH consumers using a micro-randomized trial (MRT) design. Results of this study will inform if delivering engagement strategies can meaningfully increase initial and sustained engagement with MHA resources and which types of strategies, specifically, work best for which users.

This study aims to evaluate the feasibility of testing tailored engagement strategies with SGM DMH consumers using a micro-randomized trial (MRT) design and to create preliminary evidence about which theory-driven strategies most effectively promote engagement with DMH resources. This study will involve delivering brief, theory driven engagement strategies at two key decision points within the flow of MHA's Screening Program and assess feasibility of integrating these strategies into MHA's existing web infrastructure and testing them in a naturalistic setting.

The primary objective is to evaluate whether delivering (vs. not delivering) engagement strategies after an online depression screening increases initial and sustained engagement with DMH resources on the MHA website, and to understand which engagement strategy might be most effective. The engagement strategies are grounded in the Health Action Process Approach (HAPA), including immediate behavioral determinants: outcome expectancy, self-efficacy, perceived risk, and barriers and resources.

Eligibility assessment will begin after a user completes the online depression screening (PHQ-9) hosted on the MHA website as part of their Screening Program. Users who complete the online PHQ-9 and optional demographic questions will be considered for inclusion. Those who are aged 14+ and SGM will be randomized at each decision point to either receive or not receive engagement strategies. Participants will encounter two randomization decision points embedded within the usual user flow of the MHA Screening Program.

The first decision point will be the Results page where users are typically shown information about their PHQ-9 score and provided a set of 3-4 targeted Next Steps resources. Here, participants will be randomized with equal probability (0.2) to either receive: 1) no engagement strategy (i.e., the standard Results page as usual; control), or; 2) one of four types of HAPA-based engagement strategies. Participants randomized to receive an engagement strategy will be randomized with equal probability to an engagement strategy targeting a HAPA construct: 1) outcome expectancy; 2) self-efficacy; 3) perceived risk, and; 4) barriers and resources. On the Results page, these engagement strategies will be displayed as inline messages designed to quickly reinforce a HAPA behavioral determinant before users choose their Next Steps. The second decision point will be the targeted Next Steps resource page that participants click on from the Results page. Here, participants will be randomized with equal probability (0.2) to either receive: 1) no engagement strategy (i.e., the standard Next Steps resource page as usual; control), or; 2) one of four types of HAPA-based engagement strategies. Participants randomized to receive an engagement strategy will be randomized with equal probability to an engagement strategy targeting a HAPA construct: 1) outcome expectancy; 2) self-efficacy; 3) perceived risk, and; 4) barriers and resources. On the Next Steps resource page, these HAPA-based engagement strategies will be displayed as inline cards embedded directly within the page layout. These cards function as small UI components (e.g., badges) that visually stand out but do not interrupt user navigation. Each card is delivered seamlessly near the top of the Next Steps resource page content and can be read without being redirected or leaving the page.

Randomizations are independent across decision points. Delivery of engagement strategies occurs passively within the website UI and does not alter the standard navigation flow.

The primary engagement outcome will include participants' click-through from the Results page to targeted Next Steps resources (Decision Point 1) and click-through to additional MHA content page (Decision Point 2). For participants who click to another page, sustained engagement with the targeted Next Steps Content Page will also be measured as total time (in seconds) spent on the page prior to navigating to the next page. Exploratory engagement outcomes will include the total time on MHA pages and total number of MHA pages visited beyond the Results and targeted Next Steps resource, capped at 30 minutes of inactivity, and response, if available, to outcome questions displayed on Next Steps Content Page (e.g., Was this helpful?; Did this article help increase your knowledge and understanding of mental health?; Did this article help you feel more confident in managing your mental health?; Did this article help you feel more hopeful about your mental health?). All engagement outcomes will be captured automatically through MHA's analytics system.

This study uses an iterative approach in which sequential MRTs are conducted, each requiring approximately 2300 participants to detect a meaningful difference in the primary proximal outcome between pooled HAPA-based engagement strategies and the control (i.e., delivery of any HAPA-based strategy vs. control). The number of iterations is determined by the optimization process, with engagement strategies refined between iterations. Over the study period, the set of strategies included in randomization may be refined based on accumulating evidence (e.g., restricting to the highest performing strategies). Any refinements will follow prespecified decision rules developed in consultation with MHA and will be documented to ensure transparency and analytic consistency. This approach may enable more direct comparisons and supports optimization through efficient, iterative refinement of displayed strategies over the study period while maintaining a consistent MRT framework.

Inclusion Criteria:

• Users of the Mental Health America (MHA) website engaging from Internet Protocol (IP) addresses in the United States
• Completed the PHQ-9 depression screener in English
• Answered MHA's standard demographic questions that identify users as age 14 and older
• Answered MHA's standard demographic questions that identify users as LGBTQ+.

Exclusion Criteria:

• IP addresses outside of the United States
• Do not answer MHA's standard demographic questions
• Answered MHA's standard demographic questions that identify users as age 13 and younger
• Answered MHA's standard demographic questions that identify users as not LGBTQ+.