Combined association of physical activity and screen time with health-related quality of life among primary and middle school students in China

Objective To explore the association of physical activity and screen time with health-related quality of life among students in China. Methods A total of 4 388 students (graders 4–12) were randomly selected from primary, junior and senior high schools in Nanjing, China, to take part in this cross-sectional questionnaire survey in 2018. The associations of physical activity and screen time with health-related quality of life were assessed using mixed-effects linear regression models and reported as mean difference ( MD ) and 95% confidence interval (CI). Results After adjustment for potential confounders and class-level clustering effects, students with sufficient physical activity reported an increased 0.03(95% CI = 0.01–0.05) unit of the Child Health Utility 9D (CHU9D) scores compared to their counterparts with insufficient physical activity, while participants with short screen time also recorded higher CHU9D scores 0.05(95%CI = 0.02–0.08) than those with prolonged screen time. Relative to those with insufficient physical activity and prolonged screen time, students with insufficient physical activity and short screen time 0.05(95% CI = 0.02–0.09), or students with sufficient physical activity and prolonged screen time 0.03(95%CI = -0.03–0.10), or students with sufficient physical activity and short screen time 0.08(95%CI = 0.05–0.12), respectively, reported increased CHU9D scores. Conclusion Health-related quality of life was positively associated with physical activity, but negatively with screen time. Moreover, these two factors may have a combined effect on health-related quality of life. 【摘要】 目的 了解南京地区中小学生体力活动、视屏时间与生活质量的联合效应, 为制定提高学生人群生活质量的综 合措施提供参考。 方法 2018年在南京市随机抽取小学四年级至高中三年级的4 388名学生为研究对象, 使用混合效应 模型计算组间均数差值和95%C/分析体力活动、视屏时间与生活质量之间的关联。 结果 在调整混杂因素和班级水平的 聚集性后, 与体力活动不足者相比, 体力活动充足者的健康相关生活质量评分增加0.03(95% CI =0.01~0.05);与视屏时间 达到2 h/d者相比, 视屏时间不足2 h/d者的CHU9D评分增加0.05(95% CI = 0.02~0.08);与体力活动不足且视屏时间达 到2 h/d的学生相比, 体力活动不足且视屏时间不足2 h/d者的健康相关生活质量评分增加0.05(95%CI =0.02~0.09)、体 力活动充足而视屏时间达到2 h/d者的评分增加0.03(95%C/ =-0.03~0.10)、体力活动充足且视屏时间不足2 h/d者的评 分增加0.08(95%CI =0.05~0.12)。 结论 充足体力活动和较少视屏时间均可增加中小学生人群的生活质量评分, 且两者 对生活质量评分具有联合效应。