Associations between indicators of screen time and adiposity indices in Portuguese children

ObjectivesTo examine associations between three types of screen time (TV, electronic games (EG), and personal computer (PC)) and two proxies of adiposity (body mass index (BMI) and sum of skinfolds) in children.DesignThe sample comprised 17,509 children aged 2-13 years who participated in the 2009/10 Portuguese Prevalence Study of Obesity in Childhood.MethodsComplex samples generalised linear models, using school as a cluster variable were ran separately for each combination of ST predictor and adiposity-related outcome, adjusting for covariates including age, sex, physical activity, diet, and parental factors. Missing values in predictors and covariates were imputed.ResultsWatching TV for > 2 h/day compared to < 1 h/day was associated with higher age- and sex-specific BMI standard deviation score (coefficient: 0.06, 95% CI: 0.01 to 0.12, linear trend p = 0.008) and sum of skinfolds (logged and back transformed 0.04, 0.02 to 0.07, p = < 0.001). We also found weak evidence for an inverse association between PC and BMI.ConclusionsAssociations between ST and adiposity differ by both type of ST and type of adiposity marker. Only TV viewing was consistently associated with adiposity. Studies using a single adiposity marker looking at total screen time or total sedentary behaviour time may miss or confound type-specific associations.

► TV viewing was positively associated with adiposity in children, after adjustment for covariates. ► There was evidence of an inverse association between PC time and BMI SDS, but not sum of skinfolds. ► Associations between screen time and adiposity differ by type of screen time and adiposity marker.