Development and Testing of a Smoking Cessation Intervention Using Multi-Theory Model (MTM) Among Young Adults: A Randomized Controlled Trial

The goal of this clinical trial is to evaluate whether a Multi-Theory Model (MTM)-based behavioral intervention can effectively promote smoking cessation and support behavior change in young adult cigarette smokers aged 18 to 29 in the United States. This trial focuses on whether applying theory-driven strategies such as emotional transformation, behavioral confidence, and participatory dialogue can lead to higher smoking abstinence rates and improved psychosocial outcomes compared to a standard knowledge-based smoking education control group.

The main questions it aims to answer are:

• Does the intervention lead to a greater reduction in nicotine dependence scores (measured by the Fagerström Test for Nicotine Dependence [FTND]) and an increase in quit rate among young adult smokers from baseline to 12-week follow-up?
• Does the MTM-based intervention significantly improve 7-day point prevalence abstinence (PPA) at 12 weeks compared to a knowledge-based control group?
• Does the intervention result in significant positive changes in MTM constructs such as participatory dialogue, behavioral confidence, emotional transformation, practice for change, and changes in the physical and social environment from baseline to 12-week follow-up? Researchers will compare the MTM-based intervention group (experimental arm) to a knowledge-based smoking education control group to determine whether the theory-driven program is more effective in supporting smoking cessation and behavior change among young adult smokers.

Participants will:

• Complete surveys at three time points: baseline (Week 0), post-intervention (Week 5), and follow-up (Week 12), covering demographics, smoking history, nicotine dependence (FTND), MTM constructs (via a validated 48-item scale), and self-reported quit rates.
• Be randomly assigned to one of two groups:

o MTM-Based Intervention Group: Attend four weekly 90-minute virtual group sessions covering: Week 1: Participatory dialogue, behavioral confidence, and process evaluation Week 2: Emotional transformation, environmental restructuring, and process evaluation Week 3: Practice for change, relapse prevention, and process evaluation Week 4: Social support, reward systems, and process evaluation

o Knowledge-Based Control Group: Attend four weekly 90-minute didactic virtual sessions focused on: Smoking-related health risks Overview of FDA-approved smoking cessation tools

• Undergo process evaluations using the RQFSM model (Reach, Quality, Fidelity, Satisfaction, and Management) at the end of the intervention to assess how well each program was delivered and perceived.
• Have the optional opportunity for biochemical verification of smoking abstinence using exhaled carbon monoxide (CO) testing.

This trial will be conducted entirely online and follows a randomized controlled trial (RCT) design with a 1:1 group allocation ratio. A total of 144 participants (approximately 72 per group) will be recruited, accounting for an expected attrition rate of up to 50%. This sample size was chosen to ensure sufficient power to detect statistically significant differences between the two groups (effect size f = 0.25, α = 0.05, power = 0.80).

Although the intervention will be delivered virtually, the study is affiliated with the University of Nevada, Las Vegas (UNLV), which provides IRB approval, secure data storage infrastructure, and institutional oversight (IRB Protocol #2024-453). Informed consent will be obtained electronically, and all participant data will be securely stored using encrypted Qualtrics surveys and password-protected UNLV or Google Drive servers with limited access, ensuring full confidentiality and ethical compliance.

This trial addresses a pressing public health challenge: the persistent difficulty young adults face in quitting smoking despite decades of tobacco control efforts. Young adults remain a high-risk population for relapse and are frequently underserved by conventional cessation programs. This MTM-based intervention seeks to fill this gap by targeting both behavioral and environmental barriers through structured, evidence-based strategies designed to build self-efficacy, emotional readiness, and environmental support.

The use of MTM constructs such as emotional transformation, behavioral confidence, and restructuring the physical/social environment is a key innovation that may enhance long-term cessation outcomes. Moreover, delivering the program virtually increases its potential for scalability and real-world application, making it a promising model for public health programs nationwide.

The findings of this clinical trial will be disseminated through peer-reviewed journal articles, national public health conferences (APHA, SOPHE etc.), and shared with stakeholders like the CDC's Office on Smoking and Health. The results may help shape future funding priorities, guide the development of policy, and inform the design of tailored interventions for smoking cessation among young adults.