Objective: To investigate the long-term effectiveness of a school-based intervention to improve physical activity and diet in children.
Design: Cluster-randomised controlled trial.
Setting: 60 primary schools in the southwest of England.
Participants: Primary school children who were aged 8-9 years at recruitment, 9-10 years during the intervention and 10-11 years at the long-term follow-up assessment.
Intervention: Teacher training, provision of lesson and child-parent interactive homework plans and teaching materials.
Main outcome measures: Primary outcomes were accelerometer-assessed minutes of moderate to vigorous physical activity (MVPA) per day, accelerometer-assessed minutes of sedentary behaviour per day and reported daily consumption of servings of fruit and vegetables.
Results: 60 schools with 2221 eligible children were recruited. As in the previously published assessment immediately after the end of the intervention, none of the three primary outcomes differed between children in schools allocated to the intervention, compared with those in control schools at the end of the long-term follow-up (1 year after the end of the intervention). Differences in secondary outcomes were consistent with those at the immediate follow-up, with no evidence that these had diminished over time. Comparing intervention with control schools, the difference in mean child-reported screen viewing at the weekend was -16.03 min (95% CI -32.82 to 0.73), for servings of snacks per day, the difference was -0.11 (95% CI -0.39 to 0.06), in servings of high-energy drinks per day -0.20 (95% CI -0.39 to -0.01) and in servings of high-fat foods per day -0.12 (95% CI -0.39 to 0.00). None of these reached our predefined level of statistical significance, especially after accounting for multiple testing.
Conclusions: School-based curriculum interventions alone are unlikely to have a major public health impact on children's diet and physical activity.
Trial registration number: ISRCTN50133740, Post-results.
Keywords: children; diet; physical activity; randomised controlled trial; schools.
Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.