Psychosocial mediators of screen time reduction after an intervention for students from schools in vulnerable areas: A cluster-randomized controlled trial.

Objectives: To investigate whether psychosocial variables mediate the effect of a multicomponent intervention on screen time reduction among Brazilian students from schools located in vulnerable areas.
Design: A cluster-randomized controlled trial with a 4-month follow-up.
Methods: This study was conducted with 1085 students (548 in the intervention group and 537 in the control group), aged 11-17years. The intervention strategies focused on training teachers, increasing opportunities for physical activity at school, and reducing screen time, as well as health education. The questionnaire was administered before and after intervention with questions about the amount of time spent on TV and computer/video games on weekdays and weekend days (combined screen time). The potential psychosocial mediators (attitude, self-efficacy, family and school support) were measured through validated scales. Socioeconomic status was used as control variable. Multilevel mediation analyses were conducted using a product-of-coefficients test.
Results: Psychosocial factors were not mediators of the effect of the intervention on screen time. The intervention significantly improved school support for both sexes (boys: 1.307; girls: 0.759; p<0.05) and older students (1.154; p<0.001). Attitude (boys: -0.228; 11-13years: -0.133; 14-17years: -0.152; p<0.05) and self-efficacy scales (boys: -0.040; girls: -0.104; 11-13years: -0.048; 14-17years: -0.100; p<0.05) were associated with reduced screen time.
Conclusions: The intervention produced a significant improvement of school support for both sexes, as well as older students. Enhancing attitude and self-efficacy may be a useful strategy for reducing screen time among boys and students of any age groups.
Trial Registration: ClinicalTrials.Gov: NCT02439827. Registration date: May 3, 2015.
(Copyright © 2019. Published by Elsevier Ltd.)