Brief Summary What is the purpose of this research? The goal of this study is to test a new method to help informal workers in Thailand quit smoking. The investigators seek to determine if a community-based system using digital tools (such as the Line app) is more effective than the standard care provided by local health centers.

How will the research happen?

The investigators will divide participants into two groups:

Intervention Group: This group will receive a new support system. Trained village health volunteers (VHVs) will offer brief advice and support. Participants will also receive messages and counseling through the Line application and a telephone "Quitline" (1600).

Comparison Group: This group will receive the standard care normally provided at local health centers.

The study takes place in Saraburi, Thailand, and lasts for approximately 3 months.

Who can take part?

The study team is seeking individuals who:

Are between 18 and 60 years old.

Work in jobs without formal contracts (informal workers), such as street vendors or farmers.

Currently smoke cigarettes.

Own a smartphone with internet access.

What are the research questions?

The investigators will measure four primary outcomes after 3 months to evaluate the effectiveness of the new system:

The number of smokers who received sufficient information to decide to quit.

The number of participants who intend to quit smoking.

The number of participants who successfully quit smoking (confirmed by a breath test).

The cost and value of the program compared to the health benefits gained.

Detailed Description Background and Rationale Tobacco use remains the leading cause of preventable mortality globally, accounting for approximately 8 million deaths annually. In Thailand, smoking is the third most significant risk factor for healthy life-year loss, imposing an economic burden of 87,250 million baht (0.56% of GDP). Despite national efforts, Health Region 4-particularly Saraburi Province-exhibits some of the lowest smoking screening and cessation success rates in the nation, with 6-month quit rates as low as 0.15% to 0.00% in certain areas.

The "New Normal" era, following the COVID-19 pandemic, has highlighted the need for resilient, digitally-integrated health services. Traditional hospital-based smoking cessation clinics often fail to reach "informal workers"-a vulnerable demographic (e.g., street vendors, construction laborers, farmers) who lack formal social security, earn low wages, and face significant time and transportation barriers to accessing clinic-based care.

Study Framework

This study employs Andersen's Behavioral Model of Health Services Use (ABMHSU) to analyze and address barriers to service utilization. The model categorizes influences into three factors:

Predisposing Factors: Demographic traits, social structures, and health beliefs.

Enabling Factors: Resources such as digital literacy, family support, and community infrastructure.

Need Factors: Self-perceived health symptoms and evaluated nicotine dependence (measured via the Fagerström Test for Nicotine Dependence).

The Smoking Cessation Service System Intervention

The intervention group receives a multi-faceted community-based system developed through situation analysis and stakeholder engagement. The system is built on three core pillars:

Task Redistribution (Frontline Community Workforce): The study shifts the focus from hospital-centric care to community-led intervention. Village Health Volunteers (VHVs) act as the primary frontline, conducting household screenings and recording data via mobile applications. The Community Health Board (CHB), comprising local leaders and government officers, provides policy support and monitors progress. Professional Community Nurses serve as mentors, managing complex cases and pharmacological needs via digital consultations.

Efficient Digital Communication: To overcome accessibility barriers, the system utilizes the Line Application for two-way interactive communication. This platform facilitates:

Digital Education Prescriptions: Tailored motivational messages and knowledge sets based on the participant's stage of change.

Quitline 1600 Integration: Automated and manual links to the National Quitline for proactive counseling.

Peer Support Groups: Digital communities for social reinforcement and sharing experiences.

Integrated Behavioral and Herbal Interventions: The system combines evidence-based Cognitive Behavioral Therapy (CBT) and Motivational Interviewing (MI) techniques delivered through virtual platforms. Additionally, the intervention integrates Vernonia cinerea (White Flower Grass) tea as a traditional herbal therapy. Vernonia cinerea is recognized in the Thai National List of Essential Herbal Drugs for the ability to reduce nicotine cravings by altering taste perception, offering a low-cost, accessible alternative to conventional Nicotine Replacement Therapy (NRT).

Study Design and Workflow This is a cluster-randomized controlled trial (RCT) conducted at the community level to prevent data contamination.

Intervention Arm: Participants receive the comprehensive "New Normal" system including VHV home visits, Line App support, and integrated herbal/behavioral therapy.

Comparison Arm: Participants receive "Standard Care," which consists of traditional advice-giving at sub-district health promotion hospitals without the active digital follow-up or community-led task redistribution framework.

Statistical Analysis Plan Effectiveness will be analyzed using an Intention-to-Treat (ITT) approach to ensure results reflect real-world community implementation. Baseline characteristics will be compared using Chi-squared and Wilcoxon signed-rank tests. Success-defined as continuous abstinence at 6 months-will be verified through exhaled carbon monoxide (CO) monitoring using a piCO+ Smokerlyzer®. Multiple logistic regression will be used to identify significant predictors of success while controlling for confounding variables.

Summary of Changes The investigators have synthesized the technical protocols into a structured English format suitable for the "Detailed Description" field of ClinicalTrials.gov. This includes the theoretical framework (Andersen's Model), the innovative system components (Task Redistribution and Line App), and the use of Vernonia cinerea. Specific eligibility criteria and outcome measure definitions are mentioned only in context to avoid duplication with other specific modules.

Inclusion Criteria:

• Informal worker, defined as an individual engaged in an occupation outside the formal employment system, typically lacking social security benefits or formal employment contracts (e.g., street vendors, agricultural laborers, motorcycle taxi drivers, freelancers).
• Current smoker, defined as an individual who has smoked at least one cigarette daily or non-daily within the past 30 days.
• Residing in the study area (Mueang Saraburi District) for at least 3 months prior to enrollment.
• Owns a smartphone with reliable internet access and is proficient in using mobile applications (specifically the Line Application).
• Able to speak, read, and communicate clearly in Thai.
• Willing and able to provide written informed consent to participate in the full duration of the 6-month study.

Exclusion Criteria:

• Individuals currently participating in other smoking cessation programs or concurrent clinical research studies.
• Individuals with physical or mental health conditions that may impair their ability to provide accurate information or consistently participate in digital follow-up (e.g., severe cognitive impairment, advanced terminal illness).
• Planning to relocate outside the designated study area within the next 6 months.

De-identified individual participant data that underlie the results reported in the article (including text, tables, figures, and appendices) will be made available for sharing. This data will include smoking status, nicotine dependence scores (FTND), and biochemically verified carbon monoxide (CO) levels, ensuring that all personal identifiers are removed to protect participant confidentiality.

Data will be available starting 6 months after article publication and will remain accessible for up to 5 years.

Data will be shared with researchers whose proposed use of the data has been approved by a relevant ethical committee and who provide a methodologically sound proposal. Requests should be directed to the corresponding author at surintorn.kal@mahidol.ac.th. To gain access, data requestors will be required to sign a data access agreement to ensure data security and participant privacy.

The Statistician and the Research Analysis Team are masked to the group allocation during the statistical processing phase to minimize analysis bias. To ensure the integrity of the results, the randomization code and group assignments are kept in sealed envelopes and are not revealed to the personnel performing the analysis until all statistical tests are finalized. The statistician evaluates the primary and secondary outcomes using coded identifiers (e.g., Group A and Group B) without knowledge of which cluster received the "New Normal" system intervention. Unblinding occurs only after the final analysis is complete and the research team has reached a unanimous consensus on the interpretation of the findings.

Due to the behavioral nature of the community-based intervention (use of the Line Application and Village Health Volunteer home visits), it is not possible to mask the investigators and outcome assessors during the implementation phase.