Background: The results of a cluster randomised trial testing the efficacy of a text messaging (SMS)-based program for smoking cessation in vocational school students showed no short-term effects on smoking cessation; however the program resulted in lower cigarette consumption. Furthermore, occasional smokers of the intervention group made more attempts to quit smoking than occasional smokers in the control group.
Methods: Moderator analyses were conducted to test whether program efficacy differed according to demographic, health- and smoking-related baseline variables of the participants.
Results: In daily smokers, reduction of cigarette consumption was not moderated by any of the examined baseline variables. In occasional smokers, age moderated the reduction of cigarette consumption, with a higher reduction in older students. In the subgroup of daily smokers, the intervention more often resulted in progress on the stages of health behaviour change in male smokers and in smokers with at risk drinking. Furthermore, the intervention resulted in more serious quit attempts in daily smokers aged 18 years or older.
Conclusion: The results provide information on subgroups, which particularly benefit from participation in the SMS-program.