Effectiveness of a childhood obesity prevention programme delivered through schools, targeting 6 and 7 year olds: cluster randomised controlled trial (WAVES study).

BMJ (Clinical research ed.). 2018;360:k211

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Plain language summary

Excess weight in childhood is a global problem affecting around 41 million children under the age of 5 years. In addition to physical and psychosocial health consequences in these early years, childhood excess weight is an important predictor of obesity in adulthood. The aim of the study is to assess the effectiveness of a school and family based healthy lifestyle programme (WAVES intervention) compared with usual practice, in preventing childhood obesity. The primary outcome for clinical effectiveness was the difference in BMI z scores between arms at 15 and 30 months. The study was a school based, cluster randomised, controlled trial where 200 schools were randomly selected from all state run primary schools within 35miles of the study centre (n=980). 144 eligible schools were approached to achieve the target recruitment of 54 schools. The intervention components were delivered over a period of 12 months and targeted the home and school environment. The results show that there was no overall evidence of improvement in the primary outcomes of reduction in body mass index (BMI) z scores at 15 and 30 months after a childhood obesity prevention programme was delivered through schools and targeting 6 and 7-year olds. The intervention did not have any effects on secondary anthropometric, behavioural, or clinical outcomes. A clinically significant difference in BMI z score in favour of the intervention was seen in the first cohort of schools recruited. However, post hoc analysis suggested that this outcome may have been a cohort effect as no effect was seen in group 2 schools at any time point. Authors conclude that the study intervention did not result in a statistically significant difference in BMI z score overall, and there was no evidence of effect on measured diet or physical activity levels in children. However, the lower cost components of the intervention could be considered by schools to fulfil their mandated responsibilities for education on health and wellbeing.

Abstract

OBJECTIVE To assess the effectiveness of a school and family based healthy lifestyle programme (WAVES intervention) compared with usual practice, in preventing childhood obesity. DESIGN Cluster randomised controlled trial. SETTING UK primary schools from the West Midlands. PARTICIPANTS 200 schools were randomly selected from all state run primary schools within 35 miles of the study centre (n=980), oversampling those with high minority ethnic populations. These schools were randomly ordered and sequentially invited to participate. 144 eligible schools were approached to achieve the target recruitment of 54 schools. After baseline measurements 1467 year 1 pupils aged 5 and 6 years (control: 28 schools, 778 pupils) were randomised, using a blocked balancing algorithm. 53 schools remained in the trial and data on 1287 (87.7%) and 1169 (79.7%) pupils were available at first follow-up (15 month) and second follow-up (30 month), respectively. INTERVENTIONS The 12 month intervention encouraged healthy eating and physical activity, including a daily additional 30 minute school time physical activity opportunity, a six week interactive skill based programme in conjunction with Aston Villa football club, signposting of local family physical activity opportunities through mail-outs every six months, and termly school led family workshops on healthy cooking skills. MAIN OUTCOME MEASURES The protocol defined primary outcomes, assessed blind to allocation, were between arm difference in body mass index (BMI) z score at 15 and 30 months. Secondary outcomes were further anthropometric, dietary, physical activity, and psychological measurements, and difference in BMI z score at 39 months in a subset. RESULTS Data for primary outcome analyses were: baseline, 54 schools: 1392 pupils (732 controls); first follow-up (15 months post-baseline), 53 schools: 1249 pupils (675 controls); second follow-up (30 months post-baseline), 53 schools: 1145 pupils (621 controls). The mean BMI z score was non-significantly lower in the intervention arm compared with the control arm at 15 months (mean difference -0.075 (95% confidence interval -0.183 to 0.033, P=0.18) in the baseline adjusted models. At 30 months the mean difference was -0.027 (-0.137 to 0.083, P=0.63). There was no statistically significant difference between groups for other anthropometric, dietary, physical activity, or psychological measurements (including assessment of harm). CONCLUSIONS The primary analyses suggest that this experiential focused intervention had no statistically significant effect on BMI z score or on preventing childhood obesity. Schools are unlikely to impact on the childhood obesity epidemic by incorporating such interventions without wider support across multiple sectors and environments. TRIAL REGISTRATION Current Controlled Trials ISRCTN97000586.

Functional medicine

Fundamental Clinical Imbalances : Digestive, absorptive and microbiological
Patient Centred Factors : Triggers
Environmental Inputs : Diet ; Physical exercise
Personal Lifestyle Factors : Nutrition ; Exercise and movement
Functional Laboratory Testing : Not applicable

Methodological quality

Allocation concealment : Yes

Metadata

Nutrition Evidence keywords : Bodymassindex ; BMI ; Obesity ; Obese ; Overweight ; Adiposity