Association among screen-based media ownership and the relationship between BMI and screen time among school-age children in Guangzhou urban area

Objective To analyze the association among screen-based media ownership,screen time and body mass index (BMI) among children,and to provide a scientific basis for developing family strategies to reduce sedentary behavior in children.Methods All the 9 260 subjects were recruited from grade 1-5 in 29 primary schools in 5 urban districts of Guangzhou by multistage stratified random cluster sampling method for physical examination,and their parents were offered with questionnaires.The screen-based media possession rate and screen time were compared between different subgroups.Spearman correlation analysis was used to analyze the relationship between screen time and BMI-Z-score among children.Results Possession rates of television set,video/DVD player,computer without internet access,computer with internet access were 96.22%,69.21%,33.01% and 76.19%,respectively.The rates of the 4 video products in families in public school were all higher than those in private school family(x2 =174.280,312.444,53.918,644.181,P<0.01).The median of TV time and computer game time were 1.60 h and 0.50 h,respectively.The TV time and computer game time of private school pupils were higher than those among public school children(Z=14.802,6.852,P<0.01),boys spent more time on watching TV and playing computer games than girls(Z=-2.020,-6.782,P <0.05);children in overweight/obesity subgroup spent more time on playing computer games than those in non-overweight subgroup(Z=3.074,P=0.002).BMI-Z-scores of children who owned computer with intemet access household were higher than those had no computer(Z =3.240,P =0.001).And BMI-Z-score increased with increasing time of computer game(r =-0.048,P =0.002).Conclusion Household screen-based media possession rate and the time of playing computer game among children were both associated with BMI-Z-score.Screen time is different between subgroups.Gender and types of school should be considered in the intervention of healthy lifestyle of children.