School-based intervention on healthy behaviour among Ecuadorian adolescents: Effect of a cluster-randomized controlled trial on screen-time Health behavior, health promotion and society

Background: Effective interventions on screen-time behaviours (television, video games and computer time) are needed to prevent non-communicable diseases in low- and middle-income countries. The present manuscript investigates the effect of a school-based health promotion intervention on screen-time behaviour among 12- to 15-year-old adolescents. We report the effect of the trial on screen-time after two stages of implementation. Methods: We performed a cluster-randomised pair matched trial in urban schools in Cuenca-Ecuador. Participants were adolescents of grade eight and nine (mean age 12.8∈±∈0.8 years, n∈=∈1370, control group n∈=∈684) from 20 schools (control group n∈=∈10). The intervention included an individual and environmental component tailored to the local context and resources. The first intervention stage focused on diet, physical activity and screen-time behaviour, while the second stage focused only on diet and physical activity. Screen-time behaviours, primary outcome, were assessed at baseline, after the first (18 months) and second stage (28 months). Mixed linear models were used to analyse the data. Results: After the first stage (data from n∈=∈1224 adolescents; control group n∈=∈608), the intervention group had a lower increase in TV-time on a week day (β∈=∈-15.7 min; P∈=∈0.003) and weekend day (β∈=∈-18.9 min; P∈=∈0.005), in total screen-time on a weekday (β∈=∈-25.9 min; P∈=∈0.03) and in the proportion of adolescents that did not meet the screen-time recommendation (β∈=∈-4 percentage point; P∈=∈0.01), compared to the control group. After the second stage (data from n∈=∈1078 adolescents; control group n∈=∈531), the TV-time on a weekday (β∈=∈13.1 min; P∈=∈0.02), and total screen-time on a weekday (β∈=∈21.4 min; P∈=∈0.03) increased more in adolescents from the intervention group. No adverse effects were reported. Discussion and Conclusion: A multicomponent school-based intervention was only able to mitigate the increase in adolescents' television time and total screen-time after the first stage of the intervention or in other words, when the intervention included specific components or activities that focused on reducing screen-time. After the second stage of the intervention, which only included components and activities related to improve healthy diet and physical activity and not to decrease the screen-time, the adolescents increased their screen-time again. Our findings might imply that reducing screen-time is only possible when the intervention focuses specifically on reducing screen-time. Trial registration: Clinicaltrials.gov identifier NCT01004367.