Abstract
BACKGROUND: Mobile health interventions, particularly dynamic Just-In-Time Adaptive Interventions (JITAIs), can overcome barriers to gambling treatment by offering timely, accessible support in people's everyday lives. GamblingLess: In-The-Moment is a theoretically-informed and evidence-based app-delivered JITAI to people who want to quit or reduce their gambling. The JITAI aims to reduce gambling symptom severity through short-term reductions in the likelihood of gambling episodes by improving cognitive vulnerability (craving intensity, self-efficacy, or positive outcome expectancies). It administers three daily ecological momentary assessments (EMAs) to deliver tailored interventions in moments of cognitive vulnerability. Given that intervention acceptability and engagement are likely to improve clinical outcomes, this study aimed to comprehensively examine these constructs for GamblingLess: In-The-Moment. METHODS: A 28-day micro-randomised trial (MRT) was conducted, with a supplementary six-month within-group follow-up evaluation and a mixed-methods acceptability/engagement evaluation. The acceptability/engagement evaluation included: (1) app use and engagement indices across the MRT (n = 192; 66% male; age(median)=35 years); (2) app acceptability measures administered at post-intervention (n = 161; 84% completion rate), and (3) semi-structured interviews (n = 11). RESULTS: App use and engagement indices indicated that the JITAI was an attractive option for gambling support. Participants completed 5,116 EMAs (compliance rate = 32%, averaging 27 EMAs), spent an average of 30 min in the app, and completed an average of nine intervention activities from a pool of 53 activities they could repeatedly access. Subjective quality and perceived impact scores well exceeded minimally acceptable standards but 77% of participants preferred a hybrid push-pull approach and many endorsed less frequent EMAs (52%) but a longer program (58%). Participants also endorsed additional features, such as in-person support, motivational messages, gambling feedback, saving favourite activities, online discussion boards, virtual computer coaches, and in-app rewards. Interviews revealed two distinct themes: (1) facilitation of gambling reductions through check-ins/availability, personal tailoring, seamless and holistic support, and treatment experience suitability; and (2) promoting behaviour change through enhanced awareness, goal-setting, skill-building, and positive habit formation. CONCLUSIONS: GamblingLess: In-The-Moment was highly accepted and was generally perceived as effective in supporting reductions in gambling behaviour. The findings underscore the iterative process for JITAI development and highlight several avenues for its optimisation, particularly in relation to enhancing user engagement and reducing user fatigue. TRIAL REGISTRATION: The evaluation was registered with the Australian New Zealand Clinical Trials Registry (ACTRN12622000490774) in March, 2022.