Optimizing Chatbot Reminder Timing in a Chatbot Cessation Service: A Micro-Randomized Trial
September 16, 2026 updated by: Prof. Wang Man-Ping, The University of Hong Kong
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.
Study Overview
Status
Not yet recruiting
Conditions
Intervention / Treatment
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 Type
Interventional
Enrollment (Estimated)
350
Phase
- Not Applicable
Contacts and Locations
This section provides the contact details for those conducting the study, and information on where this study is being conducted.
Study Contact
- Name: Man Ping Wang
- Phone Number: +852 3917 6636
- Email: mpwang@hku.hk
Study Locations
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Hong Kong, Hong Kong
- School of Nursing, The University of Hong Kong
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Contact:
- Man Ping Wang
- Phone Number: +852 3917 6636
- Email: mpwang@hku.hk
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Participation Criteria
Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.
Eligibility Criteria
Ages Eligible for Study
- Child
- Adult
- Older Adult
Accepts Healthy Volunteers
No
Description
Inclusion Criteria:
- 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))
Exclusion Criteria:
- Have communication difficulties (either physical or cognitive) that prevent completion of the counselling and assessments
- Having queries irrelevant to tobacco control
Study Plan
This section provides details of the study plan, including how the study is designed and what the study is measuring.
How is the study designed?
Design Details
- Primary Purpose: Health Services Research
- Allocation: N/A
- Interventional Model: Single Group Assignment
- Masking: None (Open Label)
Arms and Interventions
Participant Group / Arm |
Intervention / Treatment |
|---|---|
|
Experimental: Chatbot Cessation Service With Randomized Reminder Timing
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.
|
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.
|
What is the study measuring?
Primary Outcome Measures
Outcome Measure |
Measure Description |
Time Frame |
|---|---|---|
|
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
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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.
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Within 24 hours after each randomized reminder delivery during the 12-week chatbot cessation service period
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Secondary Outcome Measures
Outcome Measure |
Measure Description |
Time Frame |
|---|---|---|
|
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
|
Whether participants provide any reply to the chatbot after receiving a randomized weekly reminder, as recorded by the chatbot system.
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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
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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.
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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
|
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.
|
Within 48 and 72 hours after each randomized reminder delivery during the 12-week chatbot cessation service period
|
Collaborators and Investigators
This is where you will find people and organizations involved with this study.
Sponsor
Study record dates
These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.
Study Major Dates
Study Start (Estimated)
September 28, 2026
Primary Completion (Estimated)
October 31, 2027
Study Completion (Estimated)
December 31, 2027
Study Registration Dates
First Submitted
September 11, 2026
First Submitted That Met QC Criteria
September 16, 2026
First Posted (Actual)
September 17, 2026
Study Record Updates
Last Update Posted (Actual)
September 17, 2026
Last Update Submitted That Met QC Criteria
September 16, 2026
Last Verified
September 1, 2026
More Information
Terms related to this study
Keywords
Additional Relevant MeSH Terms
Other Study ID Numbers
- Chat to Quit_MRT
Plan for Individual participant data (IPD)
Plan to Share Individual Participant Data (IPD)?
NO
Drug and device information, study documents
Studies a U.S. FDA-regulated drug product
No
Studies a U.S. FDA-regulated device product
No
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