The goal of this trial is to learn if chatbot-based instant messaging 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 an engagement-focused LLM-based chatbot smoking cessation intervention have a non-inferior validated abstinence rate than the control group? 2. Will an LLM-based chatbot smoking cessation intervention have a non-inferior self-reported abstinence rate, smoking reduction rate, and smoking cessation services use rate than the control group?
Researchers will compare an LLM-based chatbot smoking-cessation intervention to a human-led instant messaging support group (brief advice based on AWARD and personalised active referral) to determine whether chatbot-based instant messaging support promotes smoking cessation.
Participants in the intervention group will receive:
1. AWARD advice 2. Personalised active referral 3. 12 weeks of chatbot-based instant messaging support (via WhatsApp)
Hong Kong residents aged 18 years or above
Smoke at least one cigarette (including heated tobacco products) per day or use an e-cigarette daily in the preceding 3 months
Able to communicate in Cantonese (including reading and writing Chinese)
Saliva cotinine level ≥30 ng/mL
Smokers who have communication barriers (either physical or cognitive)
Smokers who are currently participating in other smoking cessation programs or services
Parallel
AWARD advice
BehavioralA brief (30-60 seconds) face-to-face or remote smoking cessation advice delivered using the validated AWARD model: Ask about smoking history; Warn about high health risks (accompanied by a health warning leaflet); Advise quitting as soon as possible and setting a quit date (to qualify for contest prizes); Refer to smoking cessation services using a referral card; Do it again - repeat the intervention at each follow-up, encouraging re-quitting after relapse or relapse prevention after success.
Brief leaflet on health warning and smoking cessation
BehavioralA two-sided, colour-printed A4 leaflet covering: (1) absolute risk of death from smoking; (2) full list of diseases caused by active and second-hand smoking; (3) ten pictorial warnings of health consequences on one page for maximum impact; (4) benefits of smoking cessation; and (5) simple encouraging messages to quit.
Referral card
BehavioralA three-folded card containing brief information and highlights of existing smoking cessation services in Hong Kong, contact methods, motivational messages, and strong supporting slogans.
Self-help smoking cessation booklet
BehavioralA generic booklet provided covering: benefits of quitting, smoking-related diseases, methods to quit, how to handle withdrawal symptoms, a quitting declaration, and other practical tips.
Personalized active referral
BehavioralSmokers will be introduced to various SC services in Hong Kong (via the referral card) and motivated to use them. Well-trained SC ambassadors will assist smokers in choosing their favourite or most convenient type of service. Research staff will assist participants in booking or re-booking the SC services at the 1- and 2-month follow-ups (after very brief questionnaire surveys). Participants' contact information will be forwarded to SC service providers within 7 days, and providers are expected to contact participants within 1-2 weeks. Research staff will also monitor participants' use of SC services at each follow-up (1-, 2-, 3-, and 6-month) and, at the 1- and 2-month follow-ups, assist participants in booking or rebooking appointments if necessary. Investigators shall liaise with existing service providers and seek their assistance in promptly supporting our smokers.
12 weeks of chatbot-based instant messaging support
BehavioralParticipants in the intervention group will receive 12 weeks of instant messaging support delivered by an LLM-based chatbot (GPT-4o or newer) on WhatsApp, supporting text and audio input. Using prompt engineering, agent techniques, and Retrieval-Augmented Generation, the chatbot delivers theory-based 5As/5Rs-structured interventions alongside freeform, on-demand support, with engagement features including personalisation, proactive check-ins, and interactive Quick Commands.
12 weeks of human-led instant messaging support
BehavioralParticipants in the control group will receive 12 weeks of instant messaging support delivered by a trained human counsellor via WhatsApp. Using the same theoretical frameworks as the chatbot intervention, the counsellor will provide real-time behavioural and psychosocial support grounded in the 5As/5Rs models, Motivational Interviewing (MI), and evidence-based Behaviour Change Techniques (BCTs). The support will be personalised according to each participant's sociodemographic characteristics, smoking patterns, quit intentions, and plans.
Reminder messages
BehavioralWhatsApp messages on follow-up survey reminders.
Biochemically validated abstinence
Defined as exhaled CO level \<4ppm and saliva cotinine level ≤30 ng/ml
Biochemically validated abstinence
Defined as exhaled CO level \<4ppm and saliva cotinine level ≤30 ng/ml
Self-reported 7-day point prevalence abstinence
Smokers who did not smoke even a puff in the 7 days preceding the follow-up
Self-reported reduction
Defined by at least 50% reduction in baseline daily number of cigarettes
Self-reported use of smoking cessation service
Use of smoking cessation service at 1-, 2-, 3- and 6-month follow-ups.
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The University of Hong Kong
Lead sponsor
Hong Kong Council on Smoking and Health
Collaborator
This trial is not recruiting at the moment. You can still explore other options:
