Characteristics of participants
depression, SD, depressed
At baseline, the 5293 daily smokers who participated in the randomised trial were on average 38.6 years old (range 19–75 years, SD = 10.8), most were women (67%), most lived in France (71%), and most (59%) had a positive depression screening test. Participants smoked an average of 15.8 cigarettes per day (SD = 7.6), they smoked the first cigarette of the day on average 50 minutes (SD = 96) after waking up, and they had smoked for 17 years (SD = 10.7). Most (n = 871, 62%) of the 1407 participants who completed the 6-month follow-up questionnaire were still smoking after 6 months. Of these 871 participants, 673 reported their number of cigarettes/day both at baseline and after 6 months. They smoked an average of 9.9 cigarettes/day after 6 months (SD = 7.3), and 479 of them (71%) decreased the number of cigarettes/day, 118 (18%) did not change it, and 76 (11%) increased it between the start of the study and the 6-month survey. Of the 502 who responded after 6 months and had stopped smoking after 1 month (criterion: not smoking in the last 7 days), 147 (29%) had relapsed after 6 months and 355 (71%) were still not smoking (criterion: not smoking in the last 4 weeks at 6 months).Intervention group members liked the app more and used it more often than control group members: over a 6-month period, they used the app an average of 81 vs. 37 times, on 15 vs. 9 different days, and over a period of 75 vs. 55 days (all p < 0.001). Smoking cessation rates at follow-up were similar in the Stop-Tabac group and the control group [Compared with non-respondents to the 6-month survey, respondents were 5 years older, more likely to live in Switzerland (vs France), less likely to be depressed, and they were slightly less dependent on cigarettes. Respondents used the app about 3 times more often than non-respondents, and they used it during 2 more months (Table 