What if all children achieved WHO recommendations on physical activity? Estimating the impact on socioeconomic inequalities in childhood overweight in the UK Millennium Cohort Study

Pearce, A. , Hope, S., Griffiths, L., Cortina-Borja, M., Chittleborough, C. and Law, C. (2019) What if all children achieved WHO recommendations on physical activity? Estimating the impact on socioeconomic inequalities in childhood overweight in the UK Millennium Cohort Study. International Journal of Epidemiology, 48(1), pp. 134-147. (doi: 10.1093/ije/dyy267) (PMID:30535024) (PMCID:PMC6380318)

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Background: The World Health organization (WHO) recommends that children engage in 60 min daily moderate-to-vigorous physical activity (dMVPA). Just half of children in the UK achieve these levels (with similarly low levels in other high-income countries). Thus, the dMVPA target is a focus of national obesity strategies. However, the potential impact of increased physical activity on prevalence and inequalities in childhood overweight is unknown. Using objective data from the Millennium Cohort Study (∼18 000 children born 2000–02) we simulated a series of hypothetical physical activity intervention scenarios: achievement of the target, and more realistic increases demonstrated in trials. Methods: Predicted probabilities of overweight and obesity (using measured heights and weights at age 11) were estimated in multinomial marginal structural models, adjusting for dMVPA (measured with accelerometers at age 7) and confounding. Inequalities were assessed according to household income quintiles [risk ratios (RRs) and risk differences (RDs)]. Intervention scenarios were simulated by re-estimating predicted probabilities of overweight/obesity after manipulating (increasing) dMVPA by varying amounts, for different eligibility criteria and with varying uptake. Analyses included 6493 children with accelerometer data. Survey weights and multiple imputation addressed sampling design, attrition and item missingness. Results: In all, 27% children were overweight/obese, with relative and absolute inequalities in the expected direction; 51% children were achieving 60 min dMVPA, with those from the lowest income quintile achieving, on average, 3 min more dMVPA than those from the highest income quintile. A simulation of universal achievement of the dMVPA target reduced the prevalence of overweight/obesity to 22%, but increased relative inequalities (absolute inequalities were unchanged). Smaller increases in dMVPA (informed by intervention evidence) did little to reduce prevalence or inequalities, even when targeting high-risk groups. Conclusions: Universal achievement of the WHO dMVPA target, if attainable, would reduce prevalence of childhood overweight and obesity but not inequalities. Scale-up of more realistic interventions would have limited impact.

Item Type:Articles
Additional Information:This work was supported by the England Department of Health and Social Care Children’s Policy Research Unit (grant number 10090001). Research at the UCL Great Ormond Street Institute of Child Health and Great Ormond Street Hospital for Children receives a proportion of its funding from the Department of Health and Social Care’s National Institute for Health Research Biomedical Research Centres funding scheme. The Millennium Cohort Study is funded by grants to former and current directors of the study from the Economic and Social Research Council (Professor Heather Joshi, Professor Lucinda Platt and Professor Emla Fitzsimons) and a consortium of government funders.
Glasgow Author(s) Enlighten ID:Pearce, Dr Anna
Authors: Pearce, A., Hope, S., Griffiths, L., Cortina-Borja, M., Chittleborough, C., and Law, C.
College/School:College of Medical Veterinary and Life Sciences > School of Health & Wellbeing > MRC/CSO SPHSU
Journal Name:International Journal of Epidemiology
Publisher:Oxford University Press
ISSN (Online):1464-3685
Published Online:07 December 2018
Copyright Holders:Copyright © 2018 The Authors
First Published:First published in International Journal of Epidemiology 48(1): 134-147
Publisher Policy:Reproduced under a Creative Commons License

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