Efficacy of an optimized mobile phone-based life skills training program for addiction prevention among adolescents: results of a cluster-randomized controlled trial

2023-2024

German speaking part of Switzerland

Background: Previous studies showed the effectiveness of SmartCoach, a mobile phone-based life skills training programs for addiction prevention. However, socially stratifying factors like educational level or migration background were associated with lower program use and participation. Taking into account these differences, we subsequently optimized and tailored program elements, particularly for subgroups with low program engagement using qualitative interview data. Objectives and hypotheses: This study tested whether the optimized program version was superior to the original one in terms of efficacy and program use. We hypothesized that optimization and advanced tailoring will result in increased program efficacy and use. Methods: Two-arm, parallel-group, cluster-randomized controlled trial with assessments at baseline and follow-up after 6 months. School classes were randomized into two groups (1) an intervention group receiving the optimized program version or (2) a control group receiving the original version. Participants in both groups received up to 4 weekly text messages over 4 months in order to stimulate (1) self-management skills to cope with stress, (2) self-efficacy to resist social pressure, (3) observational learning, and (4) self-regulation. The messages included interactive features to stimulate active program engagement, such as quiz questions, message and picture contests, and integration of a friendly competition with prizes, in which program users collect credits with each interaction. The optimized program version included additional tailoring for participants with personal or parental backgrounds from non-German-speaking countries, who received shorter video clips. Furthermore, other stressors, including acculturation and quarrel with the family, were addressed and the weekly text messages were not always sent on Tuesdays but on different days of the week. Primary outcomes of this trial were quantity of alcohol use, number of days per month that nicotine-containing products were smoked, and cannabis use days. Secondary outcomes included program engagement, measured by the total number of interactions with the program, social skills, and perceived stress.

Results: A total of 1,175 students from 67 Swiss secondary and upper secondary school classes, were invited to participate in the study between March 2023 and September 2024. Of these, 890 (75.7%) students (mean age 14.9 years, 57.4% female) participated in the study. Six-month follow-up assessments were completed by 552 (62.0%) out of the 890 study participants. On average, program use did not differ between the study groups with 12.6 (SD 12.8) out of 38 possible activities completed in the intervention group and 12.5 (SD 12.7) activities in the control group (P = .18). The results concerning efficacy showed no significant differences between the study groups: based on intention-to-treat analyses, the mean alcohol use based on the Alcohol Use Disorders Identification Test (AUDIT-C) score increased by 0.3 in the intervention group and by 0.5 in the control group between baseline and follow up (P = .91). The mean number of nicotine use days in the past 30 days increased by 1.0 in the intervention group and by 2.2 in the control group (P = .45) and the mean number of cannabis use days increased by 1.2 in the intervention group and by 1.9 in the control group (P = .67). Similarly, no significant group differences were observed for changes in perceived stress with a mean change score of -0.5 from baseline to follow-up in the intervention group and -0.6 in the control group (P = .77). Concerning social skills, the mean change scores were 2.3 and 2.5 in the intervention and control group, respectively (P = .45). Moderator analyses, in which differential effects were examined with regard to gender, migration status, origin from a non-German-speaking country and socio-economic status, did not reveal any significant interaction effects. Conclusions: The results did not show improved program use or efficacy in the optimized version of the program. Possible explanations include the rather small differences between the two program versions and the low prevalence rates of substance use in this age group, which limited the statistical power of the study. Trial Registration: ISRCTN10423173 (registration date: 18/08/2023).