From awareness to action: Effects of a school-based intervention on TV viewing behavior stages and screen time guidelines knowledge in Brazilian adolescents / Da conscientização à ação: Efeitos de uma intervenção escolar nos estágios de mudança de comportamento para assistir TV e no conhecimento das diretrizes de tempo de tela em adolescentes brasileiros

The aims of the study were to verify the effect of an intervention on the stage of behavior change for TV viewing and to identify the possible mediating role of knowledge on screen time guidelines among Brazilian students. This study is a multicomponent school-based intervention conducted with 727 students (54.3% female, 13 years; 427 in the intervention group and 300 in the control group). The intervention was performed in 2017 with baseline and post-intervention assessments (over one academic year). Teacher training was carried out at the beginning of the intervention along with en-vironmental improvements, while educational curriculum such as the delivery of folders and posters were performed throughout the year. The stages of behavior change for TV viewing and knowledge of screen time guidelines were measured by a self-reported questionnaire and the structural equation modeling approach was performed. The intervention had no significant effects on stages of behavior change for TV (p = 0.744) nor did it result in significant changes on knowledge of screen time guide-lines (p = 0.741). While there was no mediation between knowledge of screen time guidelines and the effect of the intervention on stages of behavior change for TV (95%CI: -0.45;0.63), an associa-tion was found between knowledge of screen time guidelines and stages of behavior change for TV (p<0.001). In conclusion, intervention had no significant effect on the stages of behavior change for TV and no mediating effect was observed. However, enhancing awareness on screen time guidelines may positively impact the adolescent's intention to reduce TV time

Os objetivos do estudo foram verificar o efeito de uma intervenção nos estágios de mudança de comporta-mento para assistir TV e identificar o papel mediador do conhecimento sobre as recomendações de tempo de tela. A intervenção multicomponente, randomizada e controlada obteve a participação de 727 alunos em 2017 (54,3% meninas, 13 anos; 427 no grupo intervenção e 300 no grupo controle). A formação dos pro-fessores foi realizada no início da intervenção juntamente com as melhorias ambientais, enquanto as ações educativas foram realizadas ao longo do ano. Os estágios de mudança de comportamento para assistir TV e o conhecimento sobre as recomendações do tempo de tela foram mensurados por questionário auto reportado, pré e pós-intervenção (um ano letivo). Para análise dos dados foi realizada uma modelagem de equações estru-turais. Não houve efeito da intervenção nos estágios de mudança de comportamento para TV (p = 0,744) e também não houve mudanças significativas no conhecimento dos estudantes sobre as recomendações do tempo de tela (p = 0,741). Embora não tenha havido mediação entre conhecimento das recomendações do tempo de tela e o efeito da intervenção nos estágios de mudança de comportamento para TV (IC95%: -0,45;0,63), foi encontrada associação entre o conhecimento das recomendações e os estágios de mudança de comportamento para TV (p < 0,001). Conclui-se que a intervenção não teve efeito significativo nos estágios de mudança de comportamento para TV e efeito mediador. No entanto, aumentar a conscientização sobre as recomendações de tempo de tela pode impactar positivamente na intenção do adolescente de reduzir o tempo de TV

Effectiveness and moderators of a multicomponent school-based intervention on screen time devices: the Movimente cluster-randomized controlled trial.

BACKGROUND: Interventions targeting reduce screen time in adolescents are urgently needed, mainly in low and middle-income countries because of the lack of evidence. Thus, the aims of the study were to examine the effect of a cluster-randomized controlled trial on screen time (ST) devices among Brazilian adolescents and to identify possible moderators. METHODS: Movimente was a multicomponent school-based intervention that was performed in 2017 and consisted of teacher training, education curriculum, and environmental improvements. Baseline and post-intervention assessments (over one academic year) were conducted with students aged 10-16 years at baseline (baseline n = 921, [n = 538 intervention group; n = 383 control group]). A self-report questionnaire was used to measure daily minutes of device specific screen time (TV, computer, video games and smartphone) and demographic variables. Linear mixed models were used to examine intervention effects and an exploratory moderation analysis (sex, grade and socioeconomic status) was performed. RESULTS: The intervention had no significant effects on TV time (ß = - 6.4, 95% CI: - 6.1;13.4), game time (ß = - 8.2, 95% CI: - 7.2;10.8), computer time (ß = 1.1, 95% CI: - 6.3;18.5), smartphone time (ß = - 10.2, 95% CI: - 32.5;12.1), screen time (ß = - 12.8, 95% CI: - 50.5;24.8), meeting screen time guidelines (OR: 1.29, 95% CI: 0.65,2.57) and meeting screen time guidelines with smartphone (OR: 1.66, 95% CI: 0.37,7.40). There was a significant intervention effect on reducing TV time (ß = - 37.1, 95% CI: - 73.0, - 1.3) among 8th grade students only. CONCLUSIONS: The Movimente intervention was effective only for TV time among 8th grade students. Understanding how school-based interventions can improve adolescents' device specific screen time across age groups is needed. Future strategies should cover all screen-based devices. Further, there is a need for more studies in low- and-middle income countries to assist in the development of effective strategies. TRIAL REGISTRATION: Clinicaltrials.gov identifier NCT02944318 (25/10/2016).