Smoking CessationNCT07826884
Optimizing Chatbot Reminder Timing in a Chatbot Cessation Service: A Micro-Randomized Trial
A study testing Chatbot Cessation Service With Randomized Reminder Timing in people with Smoking Cessation, run by The University of Hong Kong at 1 site in Hong Kong.
Trial summary
The goal of this study is to learn whether the timing of weekly chatbot reminders affects user engagement with the chatbot cessation service. Participants enrolled in the routine chatbot cessation service will be included in a micro-randomized trial. Read more about this study
- Who is it for?
- Any age
- Conditions the study is for
- Smoking Cessation
- What is being tested?
- Chatbot Cessation Service With Randomized Reminder Timing
- Type of treatment
- Lifestyle or therapy programme
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 350 participants
- Where
- 1 siteHong Kong
- Study dates
- 28 Sep 2026to 31 Dec 2027
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages Any age
- All sexes
- No healthy volunteers
- Child, Adult, Older adult
Who may be able to join
- Able to communicate in Chinese (Cantonese)
- Have access to or are willing to use WhatsApp to access the chatbot cessation service
- Used any tobacco in the past 30 days (including all types of tobacco products such as cigarette, shisha, electronic cigarettes, and heat-not-burn (HNB))
Who cannot join
- Have communication difficulties (either physical or cognitive) that prevent completion of the counselling and assessments
- Having queries irrelevant to tobacco control
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Hong Kong1 site, 1 recruiting
- Recruiting
School of Nursing, The University of Hong Kong
Hong Kong
Man Ping Wang, +852 3917 6636, mpwang@hku.hk
About this study
Official title: A Micro-Randomized Trial to Optimize the Timing of Weekly Chatbot Reminders for User Engagement in a Chatbot Cessation Service
The goal of this study is to learn whether the timing of weekly chatbot reminders affects user engagement with the chatbot cessation service. Participants enrolled in the routine chatbot cessation service will be included in a micro-randomized trial. The delivery timing of weekly reminders will be randomly assigned across different day types and times of day during the 12-week chatbot cessation service period. The study will use routine chatbot system records to evaluate engagement after reminder delivery, including whether participants respond to the chatbot and how quickly they re-engage with the service.
Read the detailed description
Sustained user engagement remains a challenge in digital smoking cessation interventions. In this chatbot cessation service, routine weekly AI-generated reminders are used to encourage users to re-engage with chatbot-based smoking cessation support during the 12-week service period. However, the optimal timing for delivering these reminders remains uncertain. This study is an embedded micro-randomized trial conducted within the existing chatbot cessation service. The aim of this study is to evaluate whether the timing of weekly chatbot reminders influences short-term user engagement and to identify optimal reminder delivery schedules. Participants enrolled in the routine chatbot cessation service will be included in the micro-randomized trial through an opt-out approach. The trial will not introduce any additional intervention components, measurements, or study visits beyond the existing chatbot cessation service and follow-up assessments. Participation in the micro-randomized trial will only affect the timing of routine weekly reminders. During the 12-week chatbot cessation service period, excluding the initial welcoming message, the delivery timing of 11 weekly reminders will be randomized across predefined day-type and time-of-day conditions. Reminder strategy will remain unchanged. The primary proximal outcome is meaningful engagement with the chatbot within 24 hours after reminder delivery, as recorded by the chatbot system. Secondary outcomes include reply status, response latency, and meaningful engagement within 48 and 72 hours after reminder delivery. Meaningful engagement is defined as user messages relevant to smoking cessaation. The findings from this study will provide evidence to optimize the timing of routine chatbot reminders and inform future development of optimized reminder strategies and adaptive digital smoking cessation interventions.
- Conditions
- Smoking Cessation
- Being tested
- Chatbot Cessation Service With Randomized Reminder Timing
- Keywords
- Smoking cessation, Behavioral counselling, Digital health, Artificial intelligence, Chatbot, Engagement, Push notification
- Medical subject headings
- Smoking Cessation
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Chatbot Cessation Service With Randomized Reminder TimingBehavioural
The chatbot cessation service provides digital smoking cessation support through a chatbot platform. Participants receive routine chatbot-based cessation support, including scheduled weekly AI-generated reminders during the 12-week service period. Excluding the initial welcoming message, the timing of the remaining 11 weekly reminders will be repeatedly randomized at weekly decision points across predefined day-type and time-of-day conditions. The randomized component is limited to reminder delivery timing. All participants receive the same chatbot content and support.
| Study group | Role | What they receive |
|---|---|---|
| Chatbot Cessation Service With Randomized Reminder Timing | Experimental | Participants will receive the routine chatbot-based smoking cessation service for 12 weeks. Within the service, the delivery timing of weekly chatbot reminders will be repeatedly randomized at weekly decision points across predefined day-type and time-of-day conditions using a micro-randomized trial design. The reminder content and chatbot support provided to participants will remain consistent. Receives: Behavioral: Chatbot Cessation Service With Randomized Reminder Timing |
What is being measured
The primary outcome is the main question the study is designed to answer.
Meaningful engagement with chatbot within 24 hours after reminder delivery
Meaningful engagement is defined as any reply regarding smoking cessation excluding emoji and simple message like "Hi" within 24 hours after receiving a randomized weekly reminder. Engagement will be automatically recorded by the chatbot system.
Measured: Within 24 hours after each randomized reminder delivery during the 12-week chatbot cessation service period
Secondary outcomes (3)
Any chatbot reply within 24 hours after reminder delivery
Whether participants provide any reply to the chatbot after receiving a randomized weekly reminder, as recorded by the chatbot system.
Measured: Within 24 hours after each randomized reminder delivery during the 12-week chatbot cessation service period
Response latency after reminder delivery
The time interval between randomized reminder delivery and the participant's first reply to the chatbot within 72 hours after reminder delivery, as recorded by the chatbot system.
Measured: Within 72 hours after each randomized reminder delivery during the 12-week chatbot cessation service period
Extended meaningful engagement with chatbot after reminder delivery
Meaningful engagement is defined as any reply regarding smoking cessation excluding emoji and simple message like "Hi" within 48 and 72 hours after receiving a randomized weekly reminder. Engagement will be automatically recorded by the chatbot system.
Measured: Within 48 and 72 hours after each randomized reminder delivery during the 12-week chatbot cessation service period
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted17 Sep 2026
- Study start28 Sep 2026
- Primary completion31 Oct 2027 (estimated)
- Study completion31 Dec 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Smoking CessationStudies of the same condition, open and under way.
- More trials run by The University of Hong KongThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Health services research
- Allocation
- Not applicable
- Intervention model
- Single group
- Model description
- An embedded micro-randomized trial within the chatbot cessation service. Participants will remain in a single chatbot cessation service cohort and will be repeatedly randomized at each weekly decision point to receive scheduled reminders delivered under predefined day-type (weekday/weekend) and time-of-day (morning/afternoon/evening) conditions during the 12-week chatbot cessation service period.
- Masking
- None (open label)
- Enrolment
- 350 participants (estimated)
Sponsor and investigators
- Lead sponsor
- The University of Hong Kong
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Prof. Wang Man-Ping, The University of Hong Kong
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07826884
- Sponsor's protocol ID
- Chat to Quit_MRT
- Status last verified
- Sep 2026
- First submitted
- 11 Sep 2026
- Last updated
- 1 Oct 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 1 Oct 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Micro-Randomized Trial to Optimize the Timing of Weekly Chatbot Reminders for User Engagement in a Chatbot Cessation Service
- ClinicalTrials.gov ID
- NCT07826884
- Acronym / sponsor ID
- Chat to Quit_MRT
- Conditions
- Smoking Cessation
- Keywords
- Smoking cessation, Behavioral counselling, Digital health, Artificial intelligence, Chatbot, Engagement, Push notification
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 350 participants (estimated)
- Lead sponsor
- The University of Hong KongUniversity, hospital or other
- Study start
- 28 Sep 2026 (actual)
- Primary completion
- 31 Oct 2027 (estimated)
- Study completion
- 31 Dec 2027 (estimated)
- First posted
- 17 Sep 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The goal of this study is to learn whether the timing of weekly chatbot reminders affects user engagement with the chatbot cessation service. Participants enrolled in the routine chatbot cessation service will be included in a micro-randomized trial. The delivery timing of weekly reminders will be randomly assigned across different day types and times of day during the 12-week chatbot cessation service period. The study will use routine chatbot system records to evaluate engagement after reminder delivery, including whether participants respond to the chatbot and how quickly they re-engage with the service.
Detailed description
Sustained user engagement remains a challenge in digital smoking cessation interventions. In this chatbot cessation service, routine weekly AI-generated reminders are used to encourage users to re-engage with chatbot-based smoking cessation support during the 12-week service period. However, the optimal timing for delivering these reminders remains uncertain. This study is an embedded micro-randomized trial conducted within the existing chatbot cessation service. The aim of this study is to evaluate whether the timing of weekly chatbot reminders influences short-term user engagement and to identify optimal reminder delivery schedules. Participants enrolled in the routine chatbot cessation service will be included in the micro-randomized trial through an opt-out approach. The trial will not introduce any additional intervention components, measurements, or study visits beyond the existing chatbot cessation service and follow-up assessments. Participation in the micro-randomized trial will only affect the timing of routine weekly reminders. During the 12-week chatbot cessation service period, excluding the initial welcoming message, the delivery timing of 11 weekly reminders will be randomized across predefined day-type and time-of-day conditions. Reminder strategy will remain unchanged. The primary proximal outcome is meaningful engagement with the chatbot within 24 hours after reminder delivery, as recorded by the chatbot system. Secondary outcomes include reply status, response latency, and meaningful engagement within 48 and 72 hours after reminder delivery. Meaningful engagement is defined as user messages relevant to smoking cessaation. The findings from this study will provide evidence to optimize the timing of routine chatbot reminders and inform future development of optimized reminder strategies and adaptive digital smoking cessation interventions.
Study design
- Primary purpose
- Health services research
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
- Model description
- An embedded micro-randomized trial within the chatbot cessation service. Participants will remain in a single chatbot cessation service cohort and will be repeatedly randomized at each weekly decision point to receive scheduled reminders delivered under predefined day-type (weekday/weekend) and time-of-day (morning/afternoon/evening) conditions during the 12-week chatbot cessation service period.
| Arm | Type | Receives |
|---|---|---|
| Chatbot Cessation Service With Randomized Reminder Timing | Experimental | Behavioral: Chatbot Cessation Service With Randomized Reminder TimingParticipants will receive the routine chatbot-based smoking cessation service for 12 weeks. Within the service, the delivery timing of weekly chatbot reminders will be repeatedly randomized at weekly decision points across predefined day-type and time-of-day conditions using a micro-randomized trial design. The reminder content and chatbot support provided to participants will remain consistent. |
Who may qualify
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Child, Adult, Older adult
Key inclusion criteria (3 listed)
- Able to communicate in Chinese (Cantonese)
- Have access to or are willing to use WhatsApp to access the chatbot cessation service
- Used any tobacco in the past 30 days (including all types of tobacco products such as cigarette, shisha, electronic cigarettes, and heat-not-burn (HNB))
Key exclusion criteria (2 listed)
- Have communication difficulties (either physical or cognitive) that prevent completion of the counselling and assessments
- Having queries irrelevant to tobacco control
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Chatbot Cessation Service With Randomized Reminder TimingThe chatbot cessation service provides digital smoking cessation support through a chatbot platform. Participants receive routine chatbot-based cessation support, including scheduled weekly AI-generated reminders during the 12-week service period. Excluding the initial welcoming message, the timing of the remaining 11 weekly reminders will be repeatedly randomized at weekly decision points across predefined day-type and time-of-day conditions. The randomized component is limited to reminder delivery timing. All participants receive the same chatbot content and support. | Behavioural | Chatbot Cessation Service With Randomized Reminder Timing |
Primary outcome
Meaningful engagement with chatbot within 24 hours after reminder delivery
Time frame: Within 24 hours after each randomized reminder delivery during the 12-week chatbot cessation service period
Meaningful engagement is defined as any reply regarding smoking cessation excluding emoji and simple message like "Hi" within 24 hours after receiving a randomized weekly reminder. Engagement will be automatically recorded by the chatbot system.
3 secondary outcomes
Any chatbot reply within 24 hours after reminder delivery
Time frame: Within 24 hours after each randomized reminder delivery during the 12-week chatbot cessation service period
Response latency after reminder delivery
Time frame: Within 72 hours after each randomized reminder delivery during the 12-week chatbot cessation service period
Extended meaningful engagement with chatbot after reminder delivery
Time frame: Within 48 and 72 hours after each randomized reminder delivery during the 12-week chatbot cessation service period
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 1 Oct 2026.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Chatbot Cessation Service With Randomized Reminder Timing in people with Smoking Cessation, run by The University of Hong Kong at 1 site in Hong Kong.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 3 inclusion and 2 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 1 Oct 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Hong Kong. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Man Ping Wang (+852 3917 6636, mpwang@hku.hk), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Meaningful engagement with chatbot within 24 hours after reminder delivery (time frame: Within 24 hours after each randomized reminder delivery during the 12-week chatbot cessation service period). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 1 Oct 2026; AzTrials last refreshed its copy on 29 Oct 2026.