Cluster randomised controlled trial, economic and process evaluation to determine the effectiveness and cost effectiveness of a novel intervention (Healthy Lifestyles Programme, HeLP) to prevent obesity in school children

摘要

Background: Approximately one third of children in England leave primary school overweight or obese. There is little evidence of effective obesity prevention programmes for this age group.\udObjective: To determine the effectiveness and cost effectiveness of a school-based healthy lifestyles programme in preventing obesity in 9-10 year olds.\udDesign: Cluster randomised controlled trial with economic and process evaluation.\udSetting: Thirty two primary schools in Southwest England.\udParticipants: Children in Year 5 (aged 9-10 years) at recruitment and Year 7 (aged 11-12 years) at 24 month post baseline follow up.\udIntervention: The Healthy Lifestyles Programme ran over the Spring term of Year 5 into the Autumn term of Year 6 and included four phases: building a receptive environment; a drama-based healthy lifestyles week; 1:1 goal setting and reinforcement activities.\udMain outcome measures: The primary outcome measure was Body Mass Index Standard Deviation Score (BMI SDS) at 24 months post baseline measures (12 months post intervention). Secondary outcomes included waist circumference SDS, percent body fat SDS, proportion of children overweight and obese at 18 and 24 months, accelerometry assessed physical activity and food intake at 18 months, and cost effectiveness.\udResults: We recruited 32 schools and 1324 children. We had 94% follow up for the primary outcome. No difference in BMI SDS was found at 24 months (mean difference -0.02 (95% CI: -0.09, 0.05)) or 18 months (mean difference -0.02 (95% CI: -0.08, 0.05) between children in the intervention and control schools. No difference was found between intervention and control groups in waist circumference SDS or percent body fat SDS or physical activity levels. Self-reported dietary behaviours showed that at 18 months children in the intervention schools consumed fewer Energy Dense Snacks and had fewer Negative Food Markers than children in the control schools. The intervention effect on Negative Food Markers was fully mediated by ‘knowledge‘ and three composite variables, ‘confidence and motivation’, ‘family approval / behaviours & child attitudes’ and ‘behaviours and strategies’. The intervention effect on Energy Dense Snacks was partially mediated by ‘knowledge’ and the same composite variables apart from ‘behaviours and strategies’. The cost of implementing the intervention was approximately £210 per child. The intervention was not cost effective compared to control. The programme was delivered with high fidelity and engaged children, schools and families across the socioeconomic spectrum. \udLimitations: Responses to the parent questionnaire in the process evaluation were low. Although the schools in the HeLP study included a range of levels of socioeconomic deprivation, class sizes and rural and urban settings, the number of children for whom English is an additional language was considerably lower than the national average. \udConclusions: The Healthy Lifestyles Programme is not effective or cost effective in preventing overweight or obesity in 9-10 year olds.\udFuture work: Our very high levels of follow up and fidelity of intervention delivery lead us to conclude that it is unlikely that school-based programmes targeting a single age group can ever be sufficiently intense to affect weight status. New approaches are needed which affect the school, family and wider environment to prevent childhood obesity.