Clinical evidence

Smoke Free implements NICE guidance for smoking cessation as it applies to digital health. Our advisors are certified by the National Centre for Smoking Cessation and Training (NCSCT); both they and the AI chatbot follow the NCSCT’s Standard Treatment Programme which is used by Stop Smoking Services throughout the UK, and beyond. In total, the app contains more than 40 of the techniques these experts use [1]. Each of which has a large body of evidence behind it.

We have evidence that our approach is highly effective. A large randomised control trial with 28,112 participants found that people given the missions – short no-smoking tasks given daily – were almost twice as likely to remain smoke free as people given the basic features of the app (OR: 1.90, 95% CI = 1.53-2.37, p < 0.001 [2]).

A second large randomised control trial found with 57,214 participants found that users randomised to receive the chatbot were more than twice as likely to remain smoke free as people who received the missions (OR = 2.38, 95% CI = 2.19-2.58, p < .001 [3]).


“Smoke Free is the only app to deliver behavioural support according to the NCSCT Standard Treatment Programme”
Dr Andy McEwen, Executive Direction, National Centre for Smoking Cessation and Training (NCSCT)

“The Smoke Free team’s professionalism, proactivity and creativity have helped drive and maintain engagement with the app across Greater Manchester.”
Andrea Crossfield, Population Health Policy and Strategy Specialist, Greater Manchester Health and Social Care Partnership

“We have found the Smoke Free team to be extremely responsive to our requirements, and have been supportive to develop new resources to engage both the target audience and health professionals working with pregnant women and their partners. Whilst this project is still ongoing and to be evaluated, the service from Smoke Free app has been exemplary.”
Joanna Feeney, Smokefree NHS Strategic Manager

“Working in collaboration with the team to develop a robust communications plan to promote the Smoke Free app and ensure engagement has been really valuable in exploring how to reach smokers at a population level in Sheffield”
Health Improvement Principal, Sheffield City Council

User testing

The app has been built according to Apple and Android app design guidelines as well as MHRA guidance and best practice for apps. Design guidelines and best practice are regularly reviewed and the app is changed as appropriate in response.

We involve end users in all stages of the development process and have done so from the very first version of the app. User input about major new features (for example with the missions, chatbot and 4-week stop smoking plan) has been actively sought by way of one-to-one interviews, focus groups and questionnaires. We also ask our Facebook community (currently 10k strong) for feedback on new features and are establishing a user panel in the app in order to have more ways to access user views.

Users responses from the feedback process are collated and implemented into features. They are then launched to a small percentage of people selected at random to capture real-world feedback from a diverse group of users. Responses from which are also collated and implemented into the feature before it is fully released.

Once fully released we use Google Analytics to measure the effect of new additions on engagement and user satisfaction, and have added numerous feedback mechanisms into the app to capture quantitative and qualitative feedback about use of the app or specific feature. App reviews are monitored to determine features that users are happy with and those they would like changed.

Bugs and crashes are monitored daily with tools such as Firebase and Crashlytics. Major errors (defined as errors that greatly affect a small number of users or significantly affect a large number of users) are fixed within 48 hours. Smaller errors are fixed with new releases of the app, which typically take place every two weeks or so.

Our support team responds to all support requests within 1 business day, usually much less. Pro members have access to 24/7 support via an in-app chat system.

User engagement

The app has received more than 200,000 user ratings. The average rating is 4.7 out of 5, 94% of ratings have been 5 or 4-star. Only 2% of ratings have been 1 or 2-star.

Smoke Free has been downloaded by more than five million people in total and it is regularly used by 300,000 people each month from over 200 different countries and regions. There have been 16.7 million sessions of use of the app in the past year lasting an average 9m each.

Forty four percent of respondents to our questionnaire (n=168,104) said they were extremely likely to recommend the app to others, 31% said it was hugely helpful to their quit. Eighty one percent of respondents to the chatbot-specific questionnaire (n=54,368) said they were very satisfied with the bot and 80% said it was really helpful to their quit.

[1] Black, N., Johnston, M., Michie, S., Hartmann‐Boyce, J., West, R., Viechtbauer, W., Eisma, M. C., Scott, C., and de Bruin, M. (2020) Behaviour change techniques associated with smoking cessation in intervention and comparator groups of randomized controlled trials: a systematic review and meta‐regression. Addiction, 115: 2008– 2020.

[2] Crane D, Ubhi HK, Brown J and West R. Relative effectiveness of a full versus reduced version of the ‘Smoke Free’ mobile application for smoking cessation: an exploratory randomised controlled trial [version 2; peer review: 2 approved]. F1000Research 2019, 7:1524

[3] Perski, O., Crane, D., Beard, E., & Brown, J. (2019). Does the addition of a supportive chatbot promote user engagement with a smoking cessation app? An experimental study. DIGITAL HEALTH.