Adaptive Mobile Interventions to Reduce Cancer Risk Behaviors

Tobacco use remains the leading cause of preventable death, causing over 400,000 annual deaths in the United States alone. Smartphone-based interventions, particularly those leveraging real-time adaptive messaging, represent a promising yet underutilized approach to delivering personalized tobacco and cannabis treatment. The investigator's ongoing NCI funded micro-randomized trial (MRT; R01 CA246590) has shown initial feasibility in reducing smoking urges through situationally tailored cognitive-behavioral therapy (CBT) and mindfulness-based acceptance and commitment-based therapy (ACT) messages triggered by real-time contextual data (e.g., geolocation, momentary stress). To advance from a static MRT framework to a dynamic, data-driven just-in-time adaptive intervention (JITAI), this project aims to develop, test, and refine a reinforcement learning (RL) algorithm that can continuously adapt to user needs in real-time, enhancing treatment outcomes for various tobacco and cannabis products.

To ensure optimal usability and engagement, the investigators will conduct user-centered testing with the developed RL-based intervention delivery in one cohort (N=7) over 45 days. This will include usability assessment via the System Usability Scale, analysis of app interaction metrics, and semi-structured interviews to gather feedback for refining message content, timing, and design.

Study Overview

• Status: Not yet recruiting
• Conditions: Smoking Cessation
• Intervention / Treatment: Behavioral: Smartphone-based intervention messages

• Study Type: Interventional
• Enrollment (Estimated): 7
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Johannes Thrul, PhD; Phone Number: 443-318-6633; Email: jthrul@jhu.edu

Study Locations

• United States
  • Maryland
    • Baltimore, Maryland, United States, 21205
      • Johns Hopkins Bloomberg School of Public Health
      • Contact: Johannes Thrul, PhD; Phone Number: 443-318-6633; Email: jthrul@jhu.edu

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• live in the U.S.;
• are between 18 and 40 years of age;
• own a smartphone with iOS and Android operating system and GPS capabilities;
• are carrying smartphone every day;
• are willing to participate in the study for 44 days and give the research team access to the phone GPS data;
• have smoked ≥100 cigarettes in the participant's life and currently smoke at least 3 cigarettes per day on 5 or more days of the week;
• are planning to quit smoking within the next 30 days.

Exclusion Criteria:

• None

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm

Intervention / Treatment

Experimental: RL-informed intervention; Participants complete a 14-day Ecological Momentary Assessment (EMA) training phase using a smartphone app (MetricWire), during which the participant responds to up to 3 randomly prompted and cigarette-triggered EMA surveys per day while the app passively collects GPS data. These data are used to identify high-risk locations and time periods and to inform a previously trained reinforcement learning (RL) algorithm. During the subsequent 30-day intervention phase, the RL algorithm delivers personalized intervention messages (cognitive-behavioral therapy [CBT], acceptance and commitment therapy [ACT], or attention control) triggered by geofence entry at high-risk locations.

Behavioral: Smartphone-based intervention messages; Intervention messages will suggest strategies of coping with smoking urges in the moment.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in smoking urge as assessed by a single item	The primary outcome will be change in participants' rating of smoking urge in EMA-post surveys, prompted 15 minutes after intervention message delivery, and controlling for the ratings in EMA-pre surveys. Urge will be assessed by a single item on a 5-point scale, ranging from 1-5; (1-very low, to 5-very high).	15 minutes after message delivery
Change in cigarettes smoked per day in past week as assessed by a single item	The primary outcome will be change in self-reported number of cigarettes smoked per day in the past week from baseline to 45-day follow-up.	Baseline, 45-day follow-up
System Usability as assessed by the System Usability Scale (SUS)	The primary outcome will be assessment of the intervention app usability assessed by a slightly modified version of the 10-item System Usability Scale ("system" wording changed to "app"). Each item is assessed on a 5-point scale from 1 (strongly disagree) to 5 (strongly agree). The SUS total score ranges from 0-100, with higher scores indicating greater usability.	45-day follow-up

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Other tobacco product use since intervention message delivery as assessed by a single item	Other tobacco product use, including e-cigarette use, in the 15 minutes after message delivery will be assessed by a single item on a binary response scale (yes/no).	15 minutes after message delivery
Activity completion as assessed by a single item	Self-reported completion of intervention message recommendation in EMA-post surveys, prompted 15 minutes after intervention message delivery will be assessed by a single item on a binary response scale (yes/no).	15 minutes after message delivery
Self-reported 7-day point prevalence abstinence as assessed by a single item	Self-reported 7-day point prevalence abstinence (no smoking, not even a puff) will be assessed by a single item on a binary response scale (yes/no).	45-day follow-up
Smoking since intervention message delivery as assessed by a single item	Smoking in the 15 minutes after message delivery will be assessed by a single item on a binary response scale (yes/no).	15 minutes after message delivery
Change in stress as assessed by a single item	Change in rating of stress in EMA-post surveys, prompted 15 minutes after intervention message delivery, and controlling for the ratings in EMA-pre surveys. Stress will be assessed by a single item on a 5-point scale ranging from 1-5 (1-very low, to 5-very high).	15 minutes after message delivery
Change in negative affect as assessed by a single item	Change in rating of negative affect in EMA-post surveys, prompted 15 minutes after intervention message delivery, and controlling for the ratings in EMA-pre surveys. Negative affect will be assessed by a single item on a 5-point scale ranging from 1-5 (1-very low, to 5-very high).	15 minutes after message delivery
Message helpfulness as assessed by a single item	Rating of message helpfulness in EMA-post surveys, prompted 15 minutes after intervention message delivery. This will be assessed by a single item on a 5-point scale ranging from 1-5 (1-not at all helpful, to 5-extremely helpful).	15 minutes after message delivery
Change in cigarettes smoked as assessed by a single item	Change (reduction) in cigarettes smoked by at least 50% between baseline and 45-day follow-up. Reduction will be calculated based on self-reported number of cigarettes/day in the past week.	Baseline, 45-day follow-up
Tobacco quit attempt as a assessed by a single item	A tobacco quit attempt since the baseline assessment will be assessed by a single item on a binary response scale (yes/no).	45-day follow-up
Change in frequency and intensity of smoking urges as assessed by two items of the Mood and Physical Symptoms Scale (MPSS)	Change in frequency and intensity of smoking urges will be assessed by two craving items from the Assessed with the Mood and Physical Symptoms Scale (MPSS) - subscale MPSS(C). Both items will be assessed on a 6-point scale from 0 (not at all / no urges) to 5 (all the time / extremely strong). Score range 0-10. Lower score better. Both items will be combined into the MPSS(C) subscale for analysis.	Baseline, 45-day follow-up
Change in psychological flexibility as assessed by the CompACT-15	Change in psychological flexibility from baseline to 45-day follow-up will be assessed by the CompACT-15. The CompACT-15 total score ranges from 0-90, with higher scores indicating better psychological flexibility.	Baseline, 45-day follow-up
Change in smoking-specific experiential avoidance as assessed by the Avoidance and Inflexibility Scale (AIS)	Change in smoking-specific experiential avoidance from baseline to 45-day follow-up will be assessed by the Avoidance and Inflexibility Scale (AIS). Items are scored on a scale of 1-5 and combined into a total score. Score range 13-65, higher total score indicates a more avoidant and inflexible response to internal states associated with smoking.	Baseline, 45-day follow-up
Tobacco product switching as assessed by 5 questions	Switching to other tobacco products including e-cigarettes from baseline to 45-day follow-up will be assessed using questions about past 7-day use of cigarettes, e-cigarettes, cigars / cigarillos / little cigars, smokeless tobacco, and hookah / waterpipe. Participants will be coded as having switched if the participant does not report cigarette smoking, but use of another tobacco product at a follow-up assessment.	Baseline, 45-day follow-up

Collaborators and Investigators

• Sponsor: Johns Hopkins Bloomberg School of Public Health
• Collaborators: Maryland Cigarette Restitution
• Investigators: Principal Investigator: Johannes Thrul, PhD, Johns Hopkins Bloomberg School of Public Health

Study record dates

Study Major Dates

• Study Start (Estimated): May 1, 2026
• Primary Completion (Estimated): July 1, 2026
• Study Completion (Estimated): July 1, 2026

Study Registration Dates

• First Submitted: May 7, 2026
• First Submitted That Met QC Criteria: May 7, 2026
• First Posted (Actual): May 13, 2026

Study Record Updates

• Last Update Posted (Actual): May 13, 2026
• Last Update Submitted That Met QC Criteria: May 7, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Behavior; Health Behavior; Smoking Cessation
• Other Study ID Numbers: IRB00033759

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: Johns Hopkins Bloomberg School of Public Health
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; ANALYTIC_CODE

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No