Obesity case study

The EDPHiS project obesity case study is a four year project designed to assess the evidence for environmental influences on overweight and obesity in children under 8y in Scotland, and to quantify the impact of actions on the influences for which the evidence is strongest. This report describes the work of the first two phases (April 2008‐March 2010) which included a literature review, prioritisation of the evidence for further analysis and initial scoping of the likely impact of prioritised topics. Further work in the final phase will extend the quantification exercise using more detailed analysis and modelling of existing data, with wider consultation about the acceptability and feasibility of actions in the prioritised topics. The case study reviewed the literature for 24 environmental ‘chains’ of possible environmental influences on overweight and obesity in children up to 8 years of age which were modified from chains identified at stakeholder workshops held by NHS Health Scotland in 2008. A systematic review was carried out, with a focus on higher quality evidence (intervention and longitudinal studies): cross‐sectional studies and review articles were used where higher quality evidence was lacking. Some evidence was found for the majority of chains though much was from the USA and many interventions were short term or did not include overweight or obesity prevalence as an outcome. The evidence from included studies was tabulated and the case study team and other experts in the area rated each chain in two respects: the strength of the evidence and the likely effect size on overweight or obesity. Fourteen people completed the rating exercise which identified 8 chains (later reduced to 7 due to overlap of included studies) as those with the strongest evidence for action:
• Sedentary behaviour
• Physical activity in schools and nurseries
• Breast feeding and weaning practices
• Sugar sweetened soft drinks
• Snacking behaviour
• Portion size of manufactured foods
• Fast food consumption
Using estimates of the difference in energy balance between children on the lower bound of obesity and those on the upper bound of normal weight, the scope for changes in these areas to bring about the required changes of 50‐150 kcal/d difference in activity energy expenditure or food and drink energy intake were explored. The prevalence of overweight and obesity and the variation by age, sex, socio‐economic status and rural/urban area of residence in Scottish children was estimated to provide a framework to assess the need for action on these areas in the different population subgroups. The prevalence of overweight was higher in boys than girls, especially among 5‐9 year olds, and in those in middle and lower quintiles of socio‐economic status but there was little difference between those in rural and urban areas.