Association between area-based deprivation and change in body-mass index over time in primary schoolchildren: a population-based cohort study in Hampshire, UK

Abstract

BackgroundChildhood obesity is a serious health challenge. Cross-sectional evidence indicates that the burden of obesity impacts most on more deprived children, yet longitudinal research is lacking. We aimed to assess the association of home-based and school-based deprivation indices with change in childhood body-mass index (BMI) z-score and BMI status over 6 years. MethodsThis cohort study linked the National Child Measurement Programme data for Hampshire children from age 4–5 years (2007–08 to 2009–10) to 10–11 years. The dataset was analysed in two groups: 18 733 children for whom home deprivation quintiles, according to the Index of Multiple Deprivation (IMD), remained constant, and 6153 children who moved home to more deprived quintiles over time. The associations between IMD quintiles and change in BMI z-score and status, defined using the British 1990 growth reference, were analysed with multiple linear regression and multinomial logistic regression, respectively, and adjusted for age, sex, ethnicity, and school Ofsted status. Ethics approval was granted by the University of Southampton. Findings11 924 children (63·7%) remained a healthy weight, 585 (3·1%) remained overweight, 990 (5·3%) remained obese, 1560 (8·3%) became overweight, and 1921 (10·3%) became obese. Children living in the most deprived quintile increased their BMI z-score by 0·13 units more than those in the least deprived quintile (95% CI 0·08–0·19). There was no significant difference for school-based quintiles. Children attending school in the most deprived quintile were significantly more likely to remain obese (relative risk 1·93, 95% CI 1·53–2·44) and become obese (1·90, 1·55–2·32). Home-based deprivation quintiles displayed stronger associations with change in BMI status than did school-based quintiles (relative risk for remaining obese 2·23, 95% CI 1·78–2·79; becoming overweight 1·36, 1·16–1·60; and becoming obese 2·42, 2·08–2·81). Moving home to a more deprived quintile was only associated with becoming obese (1·22, 1·04–1·43). InterpretationIn Hampshire, UK, home-based deprivation level is more strongly associated with negative change in childhood adiposity than school-based deprivation level. Although schools provide ample opportunities to deliver interventions, focus should not be lost on the obesogenic home environment. This study used robust measures, and a large sample size was analysed. However, consideration of familial influences of obesity is paramount. Further research of the obesogenic environment is required, combining individual and area-based measures. FundingMSc Public Health funded by Health Education England Wessex. The funding source had no role in writing the abstract or in the decision to submit it for publication.