Potential Mediating Roles of Children's Health-Related Quality of Life and Weight-Related Behaviors in the Relationship Between Socio-Educational Advantage and Weight Status.

Background: Socioeconomic status is inversely associated with weight status in developed countries. Underlying mechanisms are still to be clarified. Our aim was to determine if weight-related behaviors and health-related quality of life (HRQoL) mediate the relationship between socio-educational advantage and weight status in Australian children 9 to 13 years of age. Methods: Secondary analysis of data collected by two cluster randomized trials (2019 wave). We measured children's ( n  = 3978) height, weight, diet, physical activity, sedentary behavior, and HRQoL. Socio-.educational advantage was assessed at school level using the Index of Community Socio-Educational Advantage (ICSEA). A counterfactual framework was used to explore potential mediators in the relationship between socio-educational disadvantage and (1) overweight/obesity and (2) BMI z-score (BMIz). Results: Low socio-educational advantage was associated with increased overweight/obesity and BMIz. The overweight/obesity association was mediated by sedentary behavior (natural indirect effect as a proportion of total, 7.5%) sugar-sweetened beverage (SSB) consumption (12.7%), physical functioning (11.9%), psychosocial health (10.9%), school (6.8%) and social functioning (15.6%), and total HRQoL score (13.8%). The ICSEA-BMIz relationship was mediated by sedentary behavior (5.7%), sleep duration (4.1%), SSB (10.6%), physical functioning (9.9%), psychosocial health (9.1%), school (5.5%) and social (13.7%) functioning, and total HRQoL score (11.7%). Conclusion: Victorian Children with low socio-educational advantage were more likely to be living with overweight or obesity. This relationship was mediated by children's sedentary behavior, SSB consumption, and HRQoL. Trial Registration: Australian New Zealand Clinical Trials Registry (ANZCTR): ACTRN12616000980437 (registered July 26, 2016, retrospectively registered) and ACTRN12618001986268 (registered December 11, 2018, prospectively registered). https://www.anzctr.org.au/Trial/Registration.