The Stop-tabac smartphone application for smoking cessation: a randomized controlled trial.

To test whether the Stop-tabac smartphone application (app) increased smoking cessation rates. A two-arm, parallel-group, individually randomized, double-blind, controlled trial. A total of 5293 daily smokers (Stop-tabac = 2639, control = 2654) enrolled on app stores and on the internet in 2019-20, who lived in France or Switzerland. The Stop-tabac application includes immediate feedback during episodes of craving and withdrawal; individually tailored counseling messages with notifications sent during 6 months; a discussion forum; fact sheets; modules on nicotine replacement therapy and e-cigarettes; and calculators of cigarettes not smoked, money saved and days of life gained since quitting. The control application included five brief pages and calculators as above. Primary outcome: self-reported smoking cessation after 6 months (no puff of tobacco in the past 4 weeks), with non-responders counted as smokers. self-reported use of nicotine medications. Participants were aged 36 years on average; 66% were women who smoked 15 cigarettes/day, and 64% screened positive for depression. Stop-tabac participants used the app over a longer period than control participants (23 versus 11 days, P < 0.001). Smoking cessation rates after 6 months were 9.9% in the Stop-tabac group versus 10.3% in the control group (odds ratio = 0.96, 95% confidence interval = 0.80-1.45, P = 0.63). Rates of use of nicotine medications after entry in the study were 38 versus 30% after 6 months (χ <sup>2</sup> = 8.3, P = 0.004) in the Stop-tabac and control groups. After 6 months, 26% of participants in the Stop-tabac group and 8% in the control group said that the app helped them 'a lot' or 'enormously' to quit smoking (χ <sup>2</sup> = 113, P < 0.001). In smokers enrolled on the app stores and the internet, allocation to the Stop-tabac smoking cessation app did not increase smoking cessation rates, but increased rates of use of nicotine medications