The increased prevalence of childhood obesity is linked with several behavioural and social factors(1). Socio-economic deprivation has traditionally been associated with poorer health and increased prevalence of overweight–obesity(Reference Wang2). The aim of the present study was to examine behavioural and social correlates of childhood overweight–obesity in a group of Northern Irish schoolchildren using data collected as part of a cluster-sampled cross-sectional study of schoolchildren. Data collected included anthropometry (height, weight) and child and/or parental questionnaires on early-life exposures (including birth weight and early infant feeding practices), physical activity (self-reported) and parental adiposity (self-reported). A GIS approach, using unit postcode address information and the Northern Ireland multiple deprivation measure (NIMDM 2005), was applied to assign an area-based rank measure of economic deprivation to each child(3). The measure, calculated at the small-scale census output area (OA) level, is based on three weighted domains of deprivation: income (41.7%); employment (41.7%); proximity to services (16.6%). Associations were estimated using logistic regression analysis and expressed as unadjusted or adjusted (for gender and/or parental weight status) OR and 95% CI.
In total 1066 children (398 aged 6–7 years, 668 aged 12–13 years) participated, with similar numbers of boys and girls. The prevalence of overweight–obesity using UK90 definitions(Reference Cole, Freemann and Preece4) was 20.8% in the 6–7 year olds and 33.3% in the 12–13 year olds. Unadjusted OR showed that higher birth weight (>3.5 kg) was associated with a 2.4-fold increased risk of being overweight–obese at age 6–7 years (P=0.004) whereas in the 12–13-year-old group female gender and low physical activity levels was associated with an increased risk of being overweight–obese (1.7-fold and 2.3-fold respectively, both P=0.001). In both age-groups unadjusted OR showed that having two parents who were overweight or obese was the strongest predictor of being overweight–obese in childhood (for the 6–7 year olds OR 3.5 (95% CI 1.6, 7.8), P=0.002; for the 12–13 year olds OR 2.7 (95% CI 1.4, 5.0), P=0.003). In the final models (adjusted for gender and/or parental adiposity status) these associations held with the factors most significantly associated with childhood obesity being birth weight >3.5 kg in 6–7 year olds and low physical activity and female gender in the 12–13 year olds. In both age-groups childhood obesity was strongly associated with both parents being overweight–obese (for 6–7 year olds OR 3.7 (95% CI 1.7, 8.5); 12–13 year olds OR 2.7 (95% CI 1.4, 5.2); both P<0.001). In contrast to other methods used for categorising socio-economic deprivation at the individual level, the GIS approach represented a low subject burden method and avoided the need for intrusive questioning about personal circumstances. Outcomes from GIS revealed no significant difference between small-scale area deprivation and risk of overweight and obesity in children. Family-based strategies to combat parental obesity and encourage physical activity in younger Northern Irish individuals are needed urgently.
