A Large Language Model (LLM)-Based Chatbot Counseling for Smoking Cessation Via "Quit to Win" 2025 (QTW2025)

The goal of this trial is to learn if LLM-based chatbot counseling works to help smoking cessation in general adult smokers. It will also learn about the experience, attitude, and perception of using an LLM-based chatbot. The main questions it aims to answer are:

1. Will LLM-based smoking cessation chatbot counseling have a higher validated abstinence rate than the control group?
2. Will LLM-based smoking cessation chatbot counseling have a higher self-reported abstinence rate, smoking reduction rate, and smoking cessation services use rate than the control group?

Researchers will compare LLM-based chatbot counseling to a usual care group (brief advice based on AWARD) to see if chatbot counseling works to promote smoking cessation.

Participants in the intervention group will receive:

1. AWARD advice
2. Personalized active referral
3. LLM-based SC chatbot counseling

Although smoking prevalence is decreasing in Hong Kong (1982: 23.3%; 2023: 9.1%), it accounts for over 7,000 deaths per year and a large amount of medical cost, long-term care and productivity loss of US$ 688 million (0.6% Hong Kong GDP). Quitting is difficult because nicotine is highly addictive. Long-term habitual tobacco smoking could foster a series of physical and psychological dependence on nicotine, and thus induce cravings and nicotine withdrawal symptoms when remaining abstinent. Tradition "one-intervention-for-all" approach cannot work optimally for overall smoking population because of the individual differences in the background characteristic and variations in response to the intervention. Intervention approaches that account for personalization and variation should be explored.

Preliminary studies suggest that AI-based chatbots can deliver structured counseling to support tobacco cessation through personalised, empathetic, and authentic conversations, thus enhancing the effectiveness of smoking cessation interventions. When integrated into social media, AI chatbots can provide timely, targeted responses and connect users with a resources on widely used platforms. A 2023 meta-analysis involving 58,796 participants further highlighted the promise of chatbots for tobacco cessation (RR=1.29, 95%CI 1.13-1.46).

In late 2022, the release of ChatGPT revolutionized AI and large language models by offering unprecedented reasoning and conversational capabilities, which enables the development of more sophisticated, human-like chatbots. Although ChatGPT (and the GenAI in general) was trained as a general-purpose virtual assistant, its tasks-specific performance can be significantly enhanced through prompt engineering. Leveraging this approach, we developed an LLM-based chatbot to autonomously deliver smoking cessation counseling according to established protocols. Our previous rule-based chatbot effectively prevented smoking relapse, and a pilot trial with an LLM-based chatbot for youth smokers (n=154) showed feasibility, achieving an 80.2% retention rate. These findings support the implementation of LLM-based chatbots for behavioral counseling and smoking cessation among adult smokers.

Therefore, our study aims to test the effectiveness of a comprehensive intervention using brief cessation advice, personalized active referral, and LLM-based chatbot counselling compared with the control group on current smokers who join the Quit to Win Contest.

Eligibility Criteria:
Inclusion Criteria:

* Hong Kong residents aged 18 or above
* Smoke at least 1 tobacco stick (includes HTP) per day or use e-cigarette daily in the past 3-month
* Able to communicate in Chinese
* Exhaled carbon monoxide level ≥4 part per million or a positive salivary cotinine test
* Able to use the instant messaging tool (e.g., WhatsApp, WeChat) for communication

Exclusion Criteria:

* Smokers who have communication barriers (either physical or cognitive).
* Smokers who are currently participating in other smoking cessation programs or services.