Just-in-Time Support for Smoking, Vaping, and Eating Urges During High-Stress Moments Among Gender and Sexual Minority Adults in Dhaka

Gender and sexual minority adults in Bangladesh experience high levels of stigma-related stress. Acute stress can trigger strong, affect-driven urges to smoke, vape, or engage in stress-attributed eating. These urges can rise and fall within minutes to hours, operating outside the reach of conventional clinic-based interventions delivered days or weeks later. This pilot micro-randomized trial (MRT) evaluates whether delivering a brief, culturally adapted support message via smartphone during moments of high self-reported stress reduces the intensity of the urge for the participant's pre-specified target behaviour, relative to no message. Over a 24-day period, 115 participants will be scheduled for up to 5 ecological momentary assessments (EMA) per day. Whenever a participant reports an acute stress level of 5 or higher (0 to 10 scale) and satisfies pre-specified privacy, safety, behavioural, and spacing criteria, the app randomizes with probability 0.5 to deliver either a brief support message or no message. By contributing multiple randomized decision points over time, each participant serves as their own micro-control. The primary outcome is the intensity of the urge for the participant's pre-specified target behaviour, measured 45 to 60 minutes after randomization. An exploratory urge assessment is also collected 10 minutes after randomization; comparing the two time points will help establish whether the support message's effect is immediate, delayed, or both, and will inform the choice of follow-up window for a future, fully powered trial. Prior to trial launch, all EMA items, message content, notification logic, and digital safety protocols will be developed and tested with community members, reviewed by a Community Advisory Board, and locked. As a pilot optimization trial, its objectives are to estimate the short-term causal effect of the prompt, to identify the contexts in which that effect is larger or smaller, and to establish whether momentary assessment and just-in-time intervention research can be delivered safely, privately, and acceptably in this high-stigma setting. The study does not evaluate long-term behavioural maintenance and does not claim to address the underlying structural stigma and discrimination that produce minority stress.

Inclusion Criteria: * Age 18 years or older * Self-identifies as a gender and/or sexual minority person * Resides in Dhaka at enrolment and expects to remain in Dhaka throughout the 24-day assessment period * Reports at least one qualifying behaviour on average at least 3 days per week during the past month: (a) smoking or vaping, or (b) eating primarily in response to stress, anxiety, or emotional distress * Owns a personal Android or iOS smartphone compatible with the study platform that is used solely by the participant and is not shared with others * Able to read, understand, and respond to simple Bangla text * Able to operate the study app independently after a structured onboarding session * Willing to complete five scheduled app-based momentary assessments per day for 24 days and additional brief follow-up assessments after randomized decision points * Provides written informed consent Exclusion Criteria: * Currently participating in another behavioural or pharmacological intervention study targeting smoking, vaping, or eating behaviour * Has a severe or unstable psychiatric condition that, based on screening and review by the study clinician, would make participation in the repeated daily assessment protocol unsafe * Is unable to operate the study app independently after structured onboarding