The Smokerface poster campaign for adolescent smoking prevention in schools: A cluster-randomized controlled trial

BACKGROUND: Tobacco use remains a leading cause of preventable morbidity and mortality and is commonly initiated in adolescence. We evaluated whether Smokerface-Poster, a low-intensity, appearance-based school campaign promoting a photoaging app, could attenuate smoking uptake among early adolescents. METHODS: In this two-arm cluster-randomized controlled trial, 126 German secondary schools (9797 grade 6/7 students; 96.0% were 11-13 years old; 51.4% male; 48.6% female) were allocated to intervention or control. Intervention schools displayed two classroom posters for 24 months. Smoking behavior was assessed at baseline and 24 months. As primary outcome, we investigated the between‑group difference in the change in 30-day smoking prevalence, with a number needed to treat (NNT) of < 100 students predefined as clinically relevant per protocol. RESULTS: Baseline smoking prevalence was 7.4% in the control vs. 7.9% in the intervention group. At 24 months post-intervention, smoking prevalence increased by 19.2 %age points in control vs. 18.1 %age points in the intervention group (number needed to treat=93; adjusted ratio of odds ratios 0.87, 95% CI 0.69-1.09; p = 0.228). Favorable, non-significant patterns were also observed for anti-smoking intentions and attitudes. CONCLUSION: Although the between-group difference was not statistically significant, the intervention reached the predefined threshold for clinical relevance, with an NNT of 93. This suggests that, for every 93 students exposed to the Smokerface-Poster campaign, one fewer adolescent would be expected to smoke over the two-year follow-up. Given its low cost of < €50 per 100 students, the intervention appears to be a promising approach to supporting school-based smoking prevention.