Impact of cigarette advertising on smoking behaviour in Spanish adolescents as measured using recognition of billboard advertising

Background: Cross-sectional studies provide empirical support for associations between advertising and adolescent smoking. The aim of this study was to investigate the relationship between Spanish adolescent smoking behaviour and prior awareness of cigarette advertisements on billboards, using a prospective design. Methods: 3,664 Spanish children aged 13 and 14 years filled in self-completion questionnaires at baseline, and 6, 12, and 18 months later (cohort study). Slides of three advertisements were projected at baseline. A multivariate logistic regression analysis was carried out to detect possible association between number of identified tobacco advertisements brands at baseline and smoking status along time, controlling ASE Model smoking determinants, smoking prevention interventions, age, gender and socio-economic status. Results: The more advertisements identified at baseline, the greater was the risk of being a smoker (p<0.0001). Final percentages of smokers were 15.8%, 16.3%, 19.3%, and 32.6%, respectively, for zero, one, two and three advertisements recognized. When confounders were controlled, the probability of being a smoker increased with the number of advertisements identified [OR 1.26 (95% CI: 1.09-1.46) after 6 months, OR 1.18 (95% CI: 1.03-1.35) after 12 months and 1.15 (95% CI: 1.02-1.30)] after 18 months. It is possible the association would have been even greater if there had not been a differential loss of smokers from the sample. Conclusion: Increased awareness of cigarette advertising was associated with a higher smoking incidence and an increased risk of Spanish children becoming smokers. It is, therefore, imperative that cigarette advertising should be banned as a matter of urgency.