Effectiveness of a multicomponent intervention on the screen time of Brazilian adolescents: non-randomized controlled study

Abstract Aim: The aim of this study was to verify the effectiveness of a multicomponent, school-based intervention in reducing screentime in adolescents according to sex. Methods: This is a non-randomized controlled intervention study focusing on cardiorespiratory fitness, body image, nutrition and physical activity. Screentime (television, computer/video game) was the secondary outcome of the intervention and was addressed using educational strategies (folders, posters, educational sessions and group discussions). Screen time was measured using a structured questionnaire validated in Brazilian adolescents and the excess time spent on-screen was defined as two hours or more daily. The effect of the intervention was analyzed by the McNemar test and logistic regression. Results: Intervention effectively reduced the proportion of adolescents exposed to more than two hours a day of computer/videogame in males from 71.7% to 57.5% (p= 0.002) and excessive time of television in females from 81.5% to 72.6% (p = 0.024), from the beginning to the end of the study in the group receiving intervention. However, no effect of intervention was found in the comparison between intervention and control groups for computer/video game time (OR = 0.822; p = 0.504) and television time (OR = 0.667; p = 0.252). Conclusion: The intervention was not effective in reducing screen time in the comparison between intervention and control groups, but it reduced the screen time of adolescents in the intervention group.

研究目的：本研究旨在验证一项多组分学校干预方案，在分性别场景下减少青少年屏幕使用时长的有效性。
方法：本研究为非随机对照干预研究，聚焦心肺适能、身体意象、营养与身体活动。屏幕使用时长（涵盖电视、电脑/电子游戏场景）为该干预的次要结局指标，通过教育策略（宣传手册、海报、教育讲座及小组讨论）开展干预。屏幕使用时长采用经巴西青少年群体验证的结构化问卷进行评估，日均屏幕暴露时长≥2小时被定义为过度屏幕使用。干预效果采用麦克尼马尔检验（McNemar test）与逻辑回归进行分析。
结果：在干预组中，从研究开始至结束，男性群体日均使用电脑/电子游戏时长超过2小时的比例从71.7%降至57.5%（p=0.002），女性群体日均看电视时长超标的比例从81.5%降至72.6%（p=0.024），干预有效降低了这两类屏幕使用时长。然而，在干预组与对照组的比较中，未发现干预对电脑/电子游戏使用时长（优势比OR=0.822；p=0.504）与电视使用时长（OR=0.667；p=0.252）存在显著干预效果。
结论：若以干预组与对照组的整体差异为评价依据，该干预方案未能有效降低青少年的整体屏幕使用时长，但可显著减少干预组青少年的屏幕使用时长。