Effectiveness and cost-effectiveness of the Daily Mile on childhood weight outcomes and wellbeing: a cluster randomised controlled trial

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  • Birmingham Services for Education


Background: The Daily Mile is designed to increase physical activity levels with children running or walking around school grounds for 15-minutes daily. It has been adopted by schools worldwide and endorsed as a solution to tackle obesity, despite no robust evidence of its benefits. We conducted a cluster-randomised controlled trial to determine its clinical and cost-effectiveness.

Methods: 40 schools were randomly assigned (1:1) to either the Daily Mile intervention or control group in which only the usual school health and wellbeing activities were implemented. The primary outcome was BMI z-score (BMIz) at 12 months follow-up from baseline, with planned subgroup analysis to examine differential effects. Primary economic analysis outcome was incremental cost per Quality-Adjusted-Life-Year (QALY) gained.

Results: Using a constrained randomisation approach, balanced on school size, baseline BMIz and proportion of pupils eligible for free school meals, 20 schools were allocated to intervention (n=1,153 participants) and 20 to control (n=1,127); 3 schools withdrew (2 intervention, 1 control). At 12 months, BMIz data were available for 18 intervention schools (n=850) and 19 control schools (n=820 participants). Using intention-to-treat analysis the adjusted mean difference (MD) in BMIz (intervention – control) was -0·036 (95% CI: - 0·085 to 0·013, p=0·146). Pre-specified subgroup analysis showed a significant interaction with sex (p=0·001) suggesting a moderate size benefit of the Daily Mile in girls (MD -0·097, 95% CI -0·156 to -0·037). This was consistent with the exploratory economic results which showed the Daily Mile to be highly cost-effective in girls (£2,492 per QALY), but not in boys, and overall to have a 76% chance of cost-effectiveness for the whole sample, at the commonly applied UK threshold of £20,000 per QALY.

Conclusions: Overall the Daily Mile had a small but non-significant effect on BMIz however it had a greater effect in girls suggesting that it might be considered as a cost-effective component of a system-wide approach to childhood obesity prevention.


Original languageEnglish
Number of pages11
JournalInternational Journal of Obesity
Early online date28 Jan 2020
Publication statusE-pub ahead of print - 28 Jan 2020