Condition category
Mental and Behavioural Disorders
Date applied
Date assigned
Last edited
Prospectively registered
Overall trial status
Recruitment status
No longer recruiting

Plain English Summary

Background and study aims
Smoking continues to be the largest cause of preventable death and disease across the world. Therefore, providing effective treatment to help smokers quit is a major public health goal. The most effective way to help people quit smoking is using medications (i.e. nicotine replacement therapy; NRT) together with high intensity behavioural support. However, behavioural therapy offered on the NHS is low intensity, and is only being accessed by 5.9% of smokers looking to quit.

In this study we will test a mobile app that delivers high intensity behavioural support to smokers looking to quit. The form of therapy delivered is cognitive behavioural therapy (CBT), which works by changing the way one thinks, and therefore, how one behaves, in challenging situations. More than 500,000 users have already downloaded the app over the past year, and we have published three pilot studies using results from this programme (PMID: 29907557, 29669708, 27777216).

The aim of this study is to investigate the effectiveness of this novel digital CBT mobile app in helping individuals to quit smoking, compared to participants receiving “very brief advice” (

Who can participate?
Adults, (male and female), aged 18 years and over who have been smoking at least 5 cigarettes a day for the past one year and would would like to quit smoking in the next 30 days.

What does the study involve?
Eligible participants will attend an initial meeting for consent and baseline questionnaires. They then receive the intervention and are monitored for smoking status and secondary outcomes at 4 weeks, 26 weeks, and 52 weeks after their quit date. Each participant will also be offered free NRT.

What are the possible benefits and risks of participating?
There are no general risks to participants associated with digital CBT, the type of therapy involved in this research study. Participants may feel emotionally uncomfortable at times as they can explore feelings and experiences. However, therapy is delivered on a positive note; participants are taught useful coping skills to manage uncomfortable feelings, and have access to a chatbot and human support with a doctor or psychologist via the app. People that quit smoking experience a withdrawal period that may include cravings, anxiety, irritability, depression, and weight gain. Participants in the treatment group are taught techniques to deal with these symptoms through cognitive behavioural therapy, and those in the control group are given advice on how to deal with such symptoms and to seek support if they feel it is needed. All participants are made aware that they can contact the research team at any point, and to contact their GP if they are at all concerned about their health as a result of their smoking cessation attempt.
Lastly, there may be some burden as a result of participants having to travel to the research centre for the initial session. However, we will primarily recruit from the area close to the research centre, and appointments will be scheduled at a convenient time for participants.

Where is the study run from?
N/A - participants will attend for their baseline visit at a number of community settings across London

When is the study starting and how long is it expected to run for?
February 2018 to January 2021 (updated 03/07/2019, previously: July 2020)

Who is funding the study?
Digital Therapeutics Inc.

Who is the main contact?
Sarrah Peerbux,

Trial website

Contact information



Primary contact

Miss Sarrah Peerbux


Contact details

Unit 118 The Record Hall
16 Baldwins Gardens
United Kingdom

Additional identifiers

EudraCT number number

Protocol/serial number


Study information

Scientific title

Randomised controlled trial assessing efficacy of a novel cognitive behavioural therapy app for smoking cessation for healthy adults


Study hypothesis

A mobile phone app-enabled cognitive behavioural therapy intervention for smoking cessation is superior to the current treatment standard (“very brief advice”) as measured by the 4-week success rate in quitting.

Ethics approval

HSC REC A, Northern Ireland. REC, 23/10/2018, ref. 18/NI/0171.

Study design

Single-blind, randomized, controlled, concealed allocation, clinical trial

Primary study design


Secondary study design

Randomised controlled trial

Trial setting


Trial type


Patient information sheet

Not available in web format, please use the contact details below to request a participant information sheet.


Tobacco use


Randomisation: Participants are randomly assigned into the treatment and control arm at a 50:50 ratio.

Group 1 (Intervention): Participants in the intervention arm receive access to a behavioral intervention (cognitive behavioral therapy; CBT) delivered through a mobile application. This consists of several sessions per week completed by the participant on their phone at their convenience, and without involvement of a healthcare professional.

Group 2 (control): Those in the control arm receive a session of “very brief advice” delivered by a trained professional immediately after randomisation. More information is available at

Duration of treatment: 4-weeks
Duration of follow-up: 1 year

We confirm that there is no wash-out period between the two trial conditions as this is not a crossover trial.

Intervention type



Drug names

Primary outcome measure

Current primary outcome measure as of 24/07/2019:
Self-reported 7-day point prevalence abstinence at 4-weeks post quit date

Previous primary outcome measure:
Abstinence at 4 weeks post agreed quit date confirmed as self-reported “no puff of smoke” (using a questionnaire) in the past 2 weeks.

Secondary outcome measures

Current secondary outcome measures as of 24/07/2019:
1. 7-day point prevalence abstinence at week 26 and 52
2. Number of quit attempts at week 4, 26, and 52
3. Client Satisfaction with the intervention at week 4 (treatment only)
4. Participant changes in confidence levels, knowledge, attitudes and perceptions related to smoking cessation at week 4
5. Participant changes in self-efficacy at week 4, 26, and 52
6. Participant changes in self-reported health and wellbeing at week 4, 26, and 52
7. Self-reported abstinence at 4-weeks post quit date confirmed by ‘no puff of smoke’ in the past two weeks
8. Sustained abstinence at 24 and 52 weeks, defined as a self-report of smoking no more than five cigarettes from 2 weeks after the target quit date

Previous secondary outcome measures:
All outcomes are assessed using questionnaires completed by the participant.
1. Successful quit attempt as defined in the primary outcome at 26 and 52 weeks
2. 7-day point prevalence abstinence at week 4, 26, and 52
3. Number of quit attempts at week 4, 26, and 52
4. Client Satisfaction with the intervention at week 4 (treatment only)
5. Participant changes in confidence levels, knowledge, attitudes and perceptions related to smoking cessation at week 4
6. Participant changes in self-efficacy at week 4, 26, and 52
7. Participant changes in self-reported health and wellbeing at week 4, 26, and 52

Overall trial start date


Overall trial end date


Reason abandoned (if study stopped)


Participant inclusion criteria

1. Aged 18 or older
2. Has been smoking at least five cigarettes a day for at least one year
3. Desires to quit in the next 30 days
4. Can attend appointments at one of several locations around London
5. Using Apple iPhone (5th generation or higher) or Android phone (version 18 or higher)
6. Working proficiency in English language

Participant type

Healthy volunteer

Age group




Target number of participants


Total final enrolment


Participant exclusion criteria

1. Currently using any other form of support for smoking cessation (including Bupropion, Varenicline, behavioural support) or any other stop smoking applications
2. Has a serious health condition (as decided by the study team)
3. Currently pregnant
4. Has a diagnosed mental health condition for which medication is currently being prescribed

Recruitment start date


Recruitment end date



Countries of recruitment

United Kingdom

Trial participating centre

United Kingdom

Sponsor information


Digital Therapeutics Inc.

Sponsor details

Unit 118 The Record Hall
16 Baldwins Gardens
United Kingdom

Sponsor type




Funder type


Funder name

Digital Therapeutics Inc.

Alternative name(s)

Funding Body Type

Funding Body Subtype


Results and Publications

Publication and dissemination plan

We will disseminate the study results through peer-reviewed scientific journals, conference presentations, and through publications on our website. We intend to publish a first paper reporting on the 4-week outcomes, followed by a second paper describing the long-term follow-up data.

IPD sharing statement: the datasets generated during and/or analysed during the current study will be made available on request. Data can be requested from Sarrah Peerbux (

Intention to publish date


Participant level data

Available on request

Basic results (scientific)

Publication list

2020 results in (added 08/10/2020)

Publication citations

Additional files

Editorial Notes

08/10/2020: Publication reference added. 08/01/2020: The total final enrolment was added. 06/01/2020: The recruitment end date was changed from 31/12/2019 to 20/11/2019. 24/07/2019: The following changes were made to the trial record: 1. The primary outcome measure was changed. 2. The secondary outcome measures were changed. 3. The rationale for the changes is as follows: The previously approved primary outcome related to the Russell Standard (i.e. self-reported abstinence in the past 2- weeks at 4-weeks post quit date). This was changed to capture self-reported 7-day point prevalence abstinence at 4-weeks. This decision was informed in-part by a recent Delphi study which found only partial compliance with the Russell Standard, as reported by smoking cessation experts. Although we acknowledge that there is a lack of consensus relating to outcome criteria in smoking cessation research, it is of our opinion that the use of 7-day point prevalence is preferable to 14-day point prevalence as it will allow for greater comparability to other studies. Of the 12 studies identified in a recent Cochrane review assessing mobile phone based smoking cessation interventions, the majority (7 studies) listed 7-day point prevalence abstinence as the primary outcome at the end of treatment. Fourteen-day point prevalence was used in only one study. Amending the primary outcome to 7-day point-prevalence allows for the results generated by this study to be compared with other studies of face- to-face, digital and other low intensity intervention smoking cessation trials. We still, however, intend on capturing abstinence as defined by the Russell Standard as a secondary outcome 03/07/2019: The following changes were made to the trial record: 1. The recruitment end date was changed from 30/06/2019 to 31/12/2019. 2. The overall end date was changed from 31/07/2020 to 31/01/2021. 3. The intention to publish date was changed from 01/09/2020 to 30/05/2021. 4. The plain English summary was updated to reflect these changes.