Funded projects

In recent years children have become less active (take less exercise), more sedentary and eat less fruit and vegetables than children did in the past. These changes affect normal healthy growth and development in children and mean that children are now more likely to be overweight or obese. Getting all children to exercise more and eat better diets would be likely to reduce the number of children who are overweight and would have other health benefits. Children would be likely to have healthier hearts, lungs, bones and muscles. We also know that children who have healthy levels of activity and intake of fruit and vegetables are more likely to have healthy levels of these behaviours as adult, which means that the health benefits of getting children to be more active, less sedentary and eat more fruit and vegetables last throughout life.

A number of studies, mostly conducted in the US, have shown that school-based interventions where children are taught about healthy diets and physical activity are effective in improving behaviours in childhood. However, there have been problems with these studies. First, they have not measured long-term effects beyond the end of the intervention. This is important because part of the beneficial effect with respect to children receiving the extra lessons could have been simply because many of these lessons were 'PE' and therefore to some extent the children were compelled to be more active. We think it is important to know whether school-based interventions have a lasting effect. Second, previous studies have relied on children or their parents reporting how active and how much TV the children watched on an average day, rather than objectively measuring this. This might have exaggerated the apparent beneficial effect of these school-based interventions. It is possible to objectively assess activity and sedentary behaviour with small devices that children wear around their waists and we have shown it is possible to do this in 9-10 year old children. Lastly, to date only three studies have been conducted in the UK. These were conducted some time ago and had important methodological weaknesses. It is not clear that interventions that are effective in the US or other counties will be here.

We have been working for three years with teachers, parents and children in primary schools (35 schools and over 1000 children age 9-10) to develop an intervention that includes teaching lessons about healthy diet and exercise and involving parents in homework activities that reinforce these messages. The results of this work show that it is possible to do this intervention in the UK and teachers, parents and children like it. The results suggest that in the short-term the intervention does increase physical activity, reduce sedentary behaviour and increase fruit and vegetable consumption.

We would now like to do a large study where we would randomly select 30 schools (750 children) to have this intervention and 30 not to have the intervention immediately (but to have it at the end of the study). We will examine how effective this intervention is in increasing physical activity, reducing sedentary behaviour and increasing fruit and vegetable consumption in 9-10 year old children immediately after it is completed and also 1 year later (to test whether there are lasting effects). We will use objective measurements of physical activity and sedentary behaviour by asking the children to wear accelerometers for 5-days, which will detail amounts and intensities of the movements the children undertake. The study will provide important information about how to improve children's health in a cost-effective way via schools.

Design: School-based cluster randomised controlled trial.

Setting: State primary and junior schools with Year 5 children (aged 9-10) in the city of Bristol. Special schools will be excluded. Participants will be Year 5 children in these schools whose parents provide opt-out consent. Children will only have measurements if they provide assent.

Target population: UK school children aged 9-10

Intervention: Schools randomised to the intervention (N=30; 750 children) will receive the intervention immediately and those randomised to control (N=30;750) after completion of the 2-year follow-up assessment. The intervention comprises: a) training for classroom teachers; b) provision of 16 lesson-plans and teaching materials, including pictures, CDs and journals; c) provision of 10 parental-child interaction homework activities (see detailed project description); d) information in the school newsletters about the importance of increasing physical activity, reducing sedentary behaviour and improving diet; e) written information for parents on how to encourage their children to eat healthily and be active; f) a healthy activity day at school for parents, teachers and children in the middle of the intervention period. Training for classroom teachers will take place over 1 day (as in the feasibility/pilot studies) and will be provided by the two teacher trainers who provided training for our feasibility/pilot studies, together with input from the applicants and the trial coordinator. At the end of the training the teachers will be provided with lesson plans and all necessary materials for the 16-lessons and 10 homework activities, as well as contact details of the trial coordinator.

Measurements of Outcome and Duration of follow-up: All outcomes will be assessed at baseline (prior to starting the intervention); 1 year later (at the end of the intervention) and 2 years later (to assess any long term impact). All three assessments will be conducted at the same time of year and will be completed by two trained fieldworkers. At each stage of assessment the following will be measured on the children:

1. Accelerometer assessment of physical activity and sedentary behaviour

We will use an ActiGraph accelerometer and will use the same protocol to that used in our feasibility/pilot work. The accelerometers will be shown to the children and verbal instructions provided in the class room with all children together. Data will be collected on three weekdays and both weekend days. The accelerometer data will be downloaded and analysed using standard protocols to define sedentary, light, moderate and vigorous levels of activity.

2. Weight, height and waist circumference

All anthropometric measurements will be completed with each child in a private room. Weight (to the nearest 0.1kg) will be measured without shoes in light clothing on a Seca digital scale. Height will be measured, to the nearest 0.1cm, without shoes using a portable Harpenden stadiometer. Waist circumference will be measured the nearest 1mm at the mid-point between the lower ribs and the pelvic bone with a flexible tape.

3. Questionnaire assessment of diet, physical activity and sedentary behaviour

All questionnaires will be combined into one document and administered in the classroom with the two fieldworkers present to answer any queries. Fruit and vegetable consumption and other dietary outcomes will be assessed using the "A Day in the Life Questionnaire" (DILQ), which was used in our feasibility/pilot studies and has been previously validated in children of this age. Fruit and vegetable consumption will be assessed using an established scoring scheme. The DILQ data will also be used to create categories of snacks, high fat food and high energy drink. As in the pilot study allocation of foods written in text to categories will be undertaken independently by two individuals with discrepancies checked by the trial coordinator. An abbreviated and updated version of a previously validated screen viewing questionnaire that was used in our feasibility/pilot study will be used . The questionnaire asks about the length of time spent doing screen based activities on the previous weekday and Saturday. Validated (in children of this age) questionnaires for assessing children's self-efficacy to change physical activity and fruit and vegetable consumption behaviour and for assessing parental support of change in these activities in their children will be used to assess our mediators.

4. Collection of information on costs: Intervention related resource use in the form of time and travel will be collected through researcher and teacher time logs. Parental time and other expenses will be collected through brief self completed questionnaires completed by parents twice (mid-point and end) during the intervention period. Researchers will also record non time resources used in the provision of lesson plans, teaching materials and parental information

Sample Size: The pilot study provided information for this calculation, including intracluster correlation coefficients (ICC). With 60 schools (~1500 pupils) we will be able to detect effects that would be of public health importance (0.25-0.30SD for each outcome) with 80-90% power at a 0.05 alpha level for all primary outcomes and similar levels of power at a 0.01 alpha level for secondary outcomes.

Analyses: Analysis and presentation of data will be in accordance with CONSORT guidelines, with the primary comparative analysis being conducted on an intention-to-treat basis and due emphasis placed on confidence intervals for the between-arm comparisons. For continuously measured outcomes we would use multivariable linear regression and for binary outcomes logistic regression. The economic evaluation from a societal perspective will take the form of a cost consequence analysis. Resources will be valued as reported by researchers, teachers and parents and using routine data sources. Random-effects regression will be used to account for clustering by schools in all analyses

Time-table: The study will be completed in 3.5 years. All schools will be recruited prior to random allocation. Baseline assessment will take place during the first 8 months. Schools (N=30) allocated to intervention will have the intervention during the first 1.5 years. Follow-up assessments will be at 1 and 2 years post baseline assessment and the final 6 months of the study will be used to complete all analyses and papers for publication.

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