NCT07649044

Brief Summary

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. 1.Will an engagement-focused LLM-based chatbot smoking cessation intervention have a non-inferior validated abstinence rate than the control group?
  2. 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?
  3. 3.AWARD advice
  4. 4.Personalised active referral
  5. 5.12 weeks of chatbot-based instant messaging support (via WhatsApp)

Trial Health

63
Monitor

Trial Health Score

Automated assessment based on enrollment pace, timeline, and geographic reach

Enrollment
998

participants targeted

Target at P75+ for not_applicable

Timeline
25mo left

Started Jun 2026

Typical duration for not_applicable

Geographic Reach
1 country

1 active site

Status
not yet recruiting

Health score is calculated from publicly available data and should be used for screening purposes only.

Trial Relationships

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Study Timeline

Key milestones and dates

First Submitted

Initial submission to the registry

June 9, 2026

Completed
6 days until next milestone

First Posted

Study publicly available on registry

June 15, 2026

Completed
5 days until next milestone

Study Start

First participant enrolled

June 20, 2026

Expected
1 year until next milestone

Primary Completion

Last participant's last visit for primary outcome

June 30, 2027

1 year until next milestone

Study Completion

Last participant's last visit for all outcomes

June 30, 2028

Last Updated

June 15, 2026

Status Verified

June 1, 2026

Enrollment Period

1 year

First QC Date

June 9, 2026

Last Update Submit

June 9, 2026

Conditions

Keywords

Large-language modelChatbotSmoking cessationDigital healthEngagement

Outcome Measures

Primary Outcomes (1)

  • Biochemically validated abstinence

    Defined as exhaled CO level \<4ppm and saliva cotinine level ≤30 ng/ml

    6-month follow-up

Secondary Outcomes (10)

  • Biochemically validated abstinence

    3-month follow-up

  • Self-reported 7-day point prevalence abstinence

    3- and 6-month follow-ups

  • Self-reported reduction

    1-, 2-, 3- and 6-month follow-ups

  • Self-reported use of smoking cessation service

    1-, 2-, 3- and 6-month follow-ups

  • Prolonged abstinence

    3-month and 6-month follow-ups

  • +5 more secondary outcomes

Study Arms (2)

Intervention group

EXPERIMENTAL
Behavioral: AWARD adviceBehavioral: Brief leaflet on health warning and smoking cessationBehavioral: Referral cardBehavioral: Self-help smoking cessation bookletBehavioral: Personalized active referralBehavioral: 12 weeks of chatbot-based instant messaging supportBehavioral: Reminder messages

Control group

ACTIVE COMPARATOR
Behavioral: AWARD adviceBehavioral: Brief leaflet on health warning and smoking cessationBehavioral: Referral cardBehavioral: Self-help smoking cessation bookletBehavioral: Personalized active referralBehavioral: 12 weeks of human-led instant messaging supportBehavioral: Reminder messages

Interventions

AWARD adviceBEHAVIORAL

A 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.

Control groupIntervention group

A 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.

Control groupIntervention group
Referral cardBEHAVIORAL

A three-folded card containing brief information and highlights of existing smoking cessation services in Hong Kong, contact methods, motivational messages, and strong supporting slogans.

Control groupIntervention group

A 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.

Control groupIntervention group

Smokers 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 assist participants in booking or rebooking appointments if necessary at the 1- and 2-month follow-ups. We shall liaise with the existing service providers and seek their assistance in supporting our smokers in a timely manner.

Control groupIntervention group

Participants 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.

Intervention group

Participants 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.

Control group

WhatsApp messages on follow-up survey reminders.

Control groupIntervention group

Eligibility Criteria

Age18 Years+
Sexall
Healthy VolunteersNo
Age GroupsAdult (18-64), Older Adult (65+)

You may qualify if:

  • 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
  • Intention to quit or reduce smoking
  • Have WhatsApp installed
  • Able to use WhatsApp for communication

You may not qualify if:

  • Currently participating in other smoking cessation programmes or using any smoking cessation drug

Contact the study team to confirm eligibility.

Sponsors & Collaborators

Study Sites (1)

Hong Kong Council on Smoking and Health (COSH)

Hong Kong, Hong Kong, 999077, Hong Kong

Location

MeSH Terms

Conditions

Smoking Cessation

Condition Hierarchy (Ancestors)

Health BehaviorBehavior

Study Officials

  • Man Ping Wang

    The University of Hong Kong

    PRINCIPAL INVESTIGATOR

Central Study Contacts

Study Design

Study Type
interventional
Phase
not applicable
Allocation
RANDOMIZED
Masking
SINGLE
Who Masked
OUTCOMES ASSESSOR
Purpose
HEALTH SERVICES RESEARCH
Intervention Model
PARALLEL
Sponsor Type
OTHER
Responsible Party
PRINCIPAL INVESTIGATOR
PI Title
Professor

Study Record Dates

First Submitted

June 9, 2026

First Posted

June 15, 2026

Study Start (Estimated)

June 20, 2026

Primary Completion (Estimated)

June 30, 2027

Study Completion (Estimated)

June 30, 2028

Last Updated

June 15, 2026

Record last verified: 2026-06

Data Sharing

IPD Sharing
Will not share

Locations