bmj · confidential: for review only 2 abstract objectives: to assess the effectiveness of a school...

Confidential: For Review Only

A cluster-randomised controlled trial to assess the

effectiveness and cost-effectiveness of a childhood obesity prevention programme delivered through schools, targeting

6-7 year old children: the WAVES study

Journal: BMJ

Manuscript ID BMJ.2017.039432

Article Type: Research

BMJ Journal: BMJ

Date Submitted by the Author: 16-May-2017

Complete List of Authors: Adab, Peymane; The University of Birmingham, Public Health, Epidemiology & Biostatistics Pallan, Miranda; University of Birmingham, School of Health and Population Sciences Lancashire, Emma; University of Birmingham, Centre for Childhood Cancer Survivor Studies, School of Health and Population Sciences, Department of Public Health and Epidemiology; WAVES study, Department of Public

Health, University of Birmingham hemming, karla; birmingham Frew, Emma; University of Birmingham, Health Economics Unit Barrett, Tim; University of Birmingham, School of Clinical and Experimental Medicine Bhopal, Raj; University of Edinburgh, Cade, Janet; Nuffield Institute for Health, Epidemiology Canaway, Alastair ; University of Warwick Clarke, Joanne; University of Birmingham Daley, Amanda; University of Birmingham, Primary Care and General Practice Deeks, Jonathan; University of Birmingham, Public Health, Epidemiology

and Biostatistics Duda, Joan; University of Birmingham, School fo Sport and Exercise Sciences Ekelund, Ulf; MRC Epidemiology Unit Gill, Paramjit; University of Birmingham Griffin, Tania; University of Birmingham McGee, Eleanor; Birmingham Community Healthcare NHS Trust Hurley, Kiya; University of Birmingham Martin, James; University of Birmingham Parry, Jayne; University of Birmingham Passmore, Sandra; Services for Education Cheng, KK; Dept of Public Health and Epidemiology

Keywords: childhood obesity prevention, cluster randomised controlled trial, Diet,

https://mc.manuscriptcentral.com/bmj

BMJ

Confidential: For Review OnlyPhysical activity, Schools, Quality of life, BMI z-score

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Title

A cluster-randomised controlled trial to assess the effectiveness and cost-effectiveness of a childhood obesity prevention

programme delivered through schools, targeting 6-7 year old children: the WAVES study

Authors:

P Adab1*, M J Pallan1, E R Lancashire1*, K Hemming1, E Frew1, T Barrett2,

R Bhopal3, JE Cade4, A Canaway5, J L Clarke1, A Daley1, J Deeks1, J Duda6, U Ekelund7,8, P Gill1, T Griffin1,

E McGee9, K Hurley1, J Martin1, J Parry1, S Passmore10, KK Cheng1.

Correspondence to:

P Adab Public Health Building, University of Birmingham, B15 2TT, UK

[email protected] Tel: 00 44 121 414 3777.

WAVES study trial investigators: University of Birmingham: Peymane Adab (Professor of

Public Health and Chief Investigator), Tim Barrett (Professor of Paediatrics), KK Cheng (Professor of Public Health and Primary Care) Amanda Daley1 (NIHR Senior Research Fellow), Jonathan J Deeks

(Professor of Biostatistics), Joan L Duda (Professor of Sport and Exercise Psychology), Emma

Frew1 (Reader in Health Economics), Paramjit Gill (Clinical Reader in Primary Care Research), Karla Hemming (Senior Lecturer in Medical Statistics), Miranda J Pallan (Senior Clinical Lecturer), Jayne

Parry1 (Professor of Policy and Public Health); University of

Cambridge, Cambridge MRC Epidemiology Unit / Norwegian School of Sport Sciences: Ulf Ekelund (Professor of Physical Activity Epidemiology and Public Health/Senior Investigator

Scientist); University of Leeds: Janet E Cade (Professor of Nutritional Epidemiology and Public

Health); The University of Edinburgh: Raj Bhopal (Bruce and John Usher Chair in Public

Health); Birmingham Community Healthcare NHS Trust: Eleanor McGee (Public Health

Nutrition Lead); Birmingham Services for Education: Sandra Passmore (Education Advisor).

Author Affiliations: 1Institute of Applied Health Research, University of Birmingham, Birmingham, UK (Professor

Peymane Adab MD) (Miranda Pallan MFPH) (Emma Lancashire PhD) (Karla Hemming PhD) (Emma Frew PhD) (Joanne Clarke PhD) (Amanda Daley PhD) (Professor Jonathan Deeks PhD) (Tania Griffin PhD) (Kiya Hurley BSc)

(James Martin BSc) (Professor KK Cheng PhD); 2School of Clinical and Experimental Medicine, University of

Birmingham; Birmingham, UK (Professor Tim Barrett PhD); 3Edinburgh Migration, Ethnicity and Health Research Group, Usher Institute of Population Health Sciences and Informatics, The University of Edinburgh, Scotland;(Professor

Raj Bhopal MD); 4Nutritional Epidemiology Group, School of Food Science and Nutrition, University of Leeds, Leeds,

UK; (Professor Janet Cade PhD); 5Warwick CTU, University of Warwick, Warwick, UK; (Alastair Canaway PhD);

6School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, UK (Professor Joan

Duda PhD); 7Cambridge MRC Epidemiology Unit, Cambridge, UK / 8Department of Sports Medicine, Norwegian

School of Sport Sciences, Oslo, Norway; (Professor Ulf Ekeland PhD); 9Birmingham Community Healthcare NHS Trust,

Birmingham, UK (Eleanor McGee); 10Services for Education, Birmingham, UK (Sandra Passmore PhD).

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Abstract

Objectives: To assess the effectiveness of a school and family based health lifestyle programme (WAVES intervention)

compared with usual practice, in preventing childhood obesity.

Design: Cluster randomised controlled trial

Setting: Primary schools from the West Midlands (UK) and their Year 1 pupils, aged 5-6 years, were eligible for

participation.

Participants: 54 schools were randomly selected from all state-run primary schools within 35 miles of the study centre,

oversampling those with high minority ethnic populations. 1467 Year 1 pupils (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 1,169

(79.7%) pupils were available at first (15 month) and second (30 month) follow up respectively.

Interventions: The 12-month intervention encouraged healthy eating and physical activity, including a daily additional

30 minute school-time physical activity opportunity, a 6-week interactive skill based programme in conjunction with

Aston Villa football club, signposting of local family physical activity opportunities through 6-monthly mail-outs and

termly school led family healthy cooking skills workshops.

Main outcome measures: The primary outcomes, assessed blind to allocation, were between-arm difference in 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 sub-set.

Results: The mean BMI z-score was non-significantly lower in the intervention, compared to the control arm at 15

months (mean difference -0.075 (95%CI:-0.183 to 0.033, P= 0.175) in the baseline adjusted models. At 30 months the

mean difference was -0.027 (95%CI=-0.137 to 0.083, P= 0.186). There was no statistically significant difference between

groups for other anthropometric, dietary, physical activity or psychological measurements.

Conclusions: The primary analyses suggest that the intervention was not effective in preventing childhood obesity.

Schools are unlikely to impact on the childhood obesity epidemic without wider support across multiple sectors and

environments.

Trial Registration: Current Controlled Trials ISRCTN97000586 (registered May 2010), trial completed

Funding: National Institute for Health Research (NIHR) Health Technology Assessment Programme (Project Reference

Number 06/85/11).

Key words: Cluster randomised trial; Childhood obesity prevention; Diet; Physical activity; Quality Adjusted Life Years;

Schools; Body mass index z-score

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What this paper adds

What is already known on this subject

Systematic reviews by the Cochrane group in 2011 and the Agency for Health Care Research and Quality in 2013 have

suggested that school based interventions could be effective in preventing childhood obesity in high income countries.

However, heterogeneity in intervention components and outcomes, inconsistent findings in relation to differential

effects on subgroups and impact on inequalities, limited data on: potential harms, process measures and long term

effects, as well as lack of data on cost-effectiveness, restrict interpretation and recommendations.

What this study adds

The WAVES study is one of the largest childhood obesity prevention trials, using a predominantly experiential

intervention, evaluated within a socioeconomic and ethnically diverse population and with longer term follow up.

Despite the methodological strengths, it did not result in any meaningful difference in measures of adiposity, dietary

intake or physical activity between arms after 15 or 30 months. Whilst such interventions can fulfil the responsibility of

schools for wider education, without upstream support they are unlikely to halt the childhood obesity epidemic.

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Introduction

Excess weight in childhood is a global problem, affecting around 41 million children under the age of 5 years1. In

addition to physical and psychosocial health consequences in these early years, childhood excess weight is an

important predictor of obesity in adulthood2, with additional adverse health and economic

3 effects. In the UK around a

quarter of children have excess weight at school entry (age 4-5 years)4. The proportion of very overweight children

doubles during the subsequent six years (from approximately 9% to 19%)4, highlighting this time period as critical for

preventive action.

Systematic reviews of childhood obesity prevention studies suggest that school based interventions may be effective in

reducing the proportion of children with excess weight5 6

. Heterogeneity of study design and interventions precludes

conclusions about which combination of components are likely to be most effective. Nevertheless, overall, longer

duration, multicomponent interventions, targeting school curricula and food/physical activity (PA) environments,

providing teacher support, and extending activities to the home/community were more likely to be associated with

positive results. However trials to date have had a number of methodological weaknesses which limit recommendations

for widespread implementation5. In particular, few previous trials reported longer term outcomes, subgroup effects or

cost-effectiveness.

Here, we report the results of the West Midlands ActiVe lifestyle and healthy Eating in School children (WAVES) study; a

cluster randomised controlled trial evaluating an intervention aiming to prevent excess weight in primary school

children. The trial sought to address the main limitations identified in previous research: use of the Medical Research

Council (MRC) framework for complex intervention development and evaluation7, inclusion of a cost-effectiveness

evaluation, a sample size large enough to detect clinically significant differences in adiposity, a comprehensive process

evaluation, assessment of longer term effects, using a range of adiposity and psychosocial measures, and an objective

measure of PA.

Methods

Trial design

This was a school-based, cluster-randomised, controlled trial evaluating the clinical and cost-effectiveness of a complex

obesity prevention intervention on primary school children’s body mass index z-scores (BMI z-score) at 15 and 30

months after baseline measurements (3 and 18-months post-intervention completion) 8. The trial was approved by NHS

Research Ethics Service (NHS REC no.10/H1202/69).

Eligibility

State primary schools in the West-Midlands (UK) within 35 miles of the study centre were eligible for inclusion (n =

980). The region includes a multi-ethnic population from diverse socioeconomic backgrounds living in rural and urban

areas. Schools with fewer than 17 Year 1 (aged 5-6 years) pupils (minimum cluster size) or schools in “special measures”

(unlikely to have capacity to contribute to study) were excluded. Within participating schools, all children in Year 1 at

recruitment were eligible for inclusion.

Interventions

Irrespective of whether children participated in measurements, intervention delivery was at school-class level to all

eligible children and their families.

Intervention development

The WAVES study intervention development process commenced in 2005. Considering 70 included studies within eight

systematic reviews, we summarised intervention components incorporated in previous childhood obesity prevention

trials in relation to setting, target behaviour and type of activity. We then conducted focus groups with parents, school

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staff and local health, government and community members, to help prioritise intervention components. The

discussions considered the perceived importance and feasibility of implementation of techniques (e.g. reward

behaviours, role model, exposure to PA opportunities), activities (e.g. education materials, cooking workshops) and

particular settings (e.g. school curriculum, community setting). Prioritised ideas were checked against available local

resources and with input from an expert group of professionals, the intervention package was formed. This comprised

activities within two broad aims: increasing children’s physical activity levels through school and home; and supporting

health-behaviour skill development in families through activity based learning9. The intervention was further refined

following a feasibility study10

. The feasibility study showed that the proposed measurements could be completed

successfully (measurements obtained for 574 out of 606 children with consent (94%) at baseline) and that loss to follow

up two years after baseline was at an acceptable level (follow up measurements obtained for 83% and 86% of children

in control and intervention schools, respectively). The feasibility study was not powered to investigate intervention

outcomes but the direction of effect was in favour of the intervention for most outcomes. In particular children in the

intervention compared to the control arm had significantly lower adjusted BMI z-score at follow up (-0.15 kg/m2, 95%CI

-0.27, -0.03). Details of the finalised intervention are provided in Table 1 with a brief outline given below.

WAVES study intervention and its delivery

The intervention components, delivered over 12 months, targeted the home and school environment. Based on

findings from the feasibility study, the target group was Year 2 children (aged 6-7 years) and their families. Several

behaviour change strategies were employed to encourage increased PA and improved diet quality. School staff were

provided with training and resources for intervention delivery. A termly family newsletter reinforced messages

delivered through the various intervention components. The intervention programme (summarised in table 1)

comprised four overlapping components: 1) 30 minutes of additional moderate to vigorous physical activity on each

school day - at least 15 minutes to be outside of break times but class teachers customised timing of delivery and exact

activities undertaken according to their class circumstances, supported by resources supplied as part of the study; 2)

termly school-time cooking workshops which parents were invited to attend to participate alongside their child and

that were preceded by short classroom sessions for the children. All school staff responsible for implementation

attended a one day training session and all presentation and interactive activity materials together with take home

information sheets and suggested lesson/workshop plans were provided to minimise teacher preparation time and try

to ensure delivery of consistent nutritional messages, but timing of sessions and how parents were involved was left to

the discretion of teachers; 3) a six week programme (Villa Vitality (VV)) developed to encourage healthy eating and

increase physical activity and delivered by staff from an iconic sporting institution – school classes spent two days

undertaking activities at an English premier league football club separated by a six week period during which class

teachers were asked to spend curriculum time working on a class project and involving children and their parents with

weekly health challenges, the elements undertaken in the school were customised by the class teacher but supported

by a school visit from a VV member of staff; 4) information sheets signposting children and their families to i) ways to

be active over the summer (identical for all schools) and ii) physical activity opportunities in their local area-(school

specific sheets produced by the study team and checked prior to distribution by the school).

Comparator intervention

Schools allocated to the comparator arm continued with ongoing Year 2 health-related activities. In addition, we

provided citizenship education resources, excluding topics related to healthy eating and PA.

Outcomes

The primary outcome for clinical effectiveness was the difference in BMI-z scores between arms at 15 and 30 months

and for cost-effectiveness was cost per Quality Adjusted Life Year (not reported here). Pre-specified secondary outcome

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measures are summarised in Box 1. All outcomes were assessed at 15- and 30-months post-baseline measures (3 and

18 months post- intervention). Further details on the methods, including standardised operating procedures for all

primary and secondary outcome measurements are available in the WAVES study final report that will be available soon

via the National Institute for Health Research website (https://www.journalslibrary.nihr.ac.uk).

Implementation

Sampling and subsequent randomisation were undertaken by the Trial Statistician (KH), whilst the Trial Coordinator

(ERL) recruited schools. Schools were stratified by ethnic mix of pupils, and a weighted random sampling strategy was

used to increase the selection likelihood (3:1) of schools with a higher minority ethnic population, to enable subgroup

analysis. Using this method, 200 schools were selected, ordered using a random number generator and sequentially

invited to participate (see Figure 1 for further details of school recruitment and trial arm allocation). To allow

measurement of a large number of children in a limited timeframe within study resources, schools were recruited and

randomised in two Groups (27 schools per Group), one year apart. Parental informed consent was sought and verbal

child assent was obtained for all measurements undertaken.

Participant assessment and data collection procedures

Baseline assessment took place when children were at the end of Year 1 (aged 5-6 years). Outcome assessments, using

identical procedures, were undertaken at 15 (follow up 1) and 30 months (follow up 2) post-baseline (aged 7-8 and 8-9

years). In schools recruited in the first year (Group 1), children were further assessed at 39 months (follow up 3) post-

baseline (aged 9-10 years). Data were collected from school records, direct assessment of participating children in

school, and from parent questionnaires distributed at the time of pupil measurements. Assessments were undertaken

by trained research staff using standardised protocols and validated instruments as detailed in the protocol8 and

summarised in Table 2.

Sample size

Sample size was based on the primary outcome (BMI z-score), taking into account repeated measures (estimated

correlation between measures = 0.9), varying cluster size (assuming mean cluster size of 25, standard deviation(SD) of

23) and likely estimates of the intraclass correlation coefficient (ICC = 0 to 0.04). In order to detect a clinically

meaningful difference of 0.25 BMI z-score11

between intervention and comparator groups with 90% power, a two sided

α of 0.05 and estimated pupil dropout rate of 20%, a follow up sample of 1000 children from 50 schools was needed.

Allowing for school drop out of 8%, we recruited 54 schools to take part. This sample size also provides more than 80%

power to detect a 0.125 difference in BMI z-score (clinically important difference for prevention12

, and a difference in

the change of proportion of children who are overweight/obese from baseline to follow-up in control compared to

intervention schools of approximately 7%.

Randomization

A blocked balancing algorithm was used to randomise participating schools to intervention or comparator arms. The

algorithm randomly selected one of a number of allocation designs which minimised the imbalance between a set of

pre-specified covariate means. Included covariates were: percentage of pupils eligible for free school meals (measure of

deprivation); proportion pupils from South Asian, black African or Caribbean, White or other ethnic groups; and school

size. The first 27 schools (Group 1) were randomised within the first block; and a year later the remaining 27 schools

(Group 2) were randomised, conditioning the balancing algorithm for the first block allocations.

Randomisation took place after baseline measurements. Thus researchers, schools and their participating pupils were

not aware of arm allocation until after consent and baseline measurements were completed. Further data collection

was mainly undertaken by sessional researchers who were blind to arm allocation.

Statistical methods

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Analyses of all outcomes were by intention to treat and are reported at 15, 30 and 39 months after baseline (3, 18 and

27 months after the end of the intervention). For the primary analyses (complete case analysis), we used mixed linear

regression models for all continuous outcomes (e.g. BMI z-score), and Poisson mixed regression for binary outcomes to

allow estimation of adjusted risk differences consistent with CONSORT guidelines. To accommodate any non-normality

of the outcomes, data were transformed where necessary and where such transformation improved the model. The

baseline adjustment model included the baseline measurement and treatment arm as the independent variables, and

school as the random effect. We also report models adjusted for pre-specified baseline school and child level covariates

(covariates are listed in results tables). Planned sub-group analyses, using interaction tests, examined whether any

intervention effects differed by ethnicity, sex, socio-economic status or baseline weight status.

Sensitivity analyses included using multiple imputation (using chained equations) for missing values for each outcome,

exploring cluster heterogeneity by time period (Group 1 vs Group 2 schools) and methods of adjusting for missing

baseline variables to maximise use of available data and heterogeneity of ICC in intervention and control arms.

Additional details on the statistical methods are available in the final report that will be available via the National

Institute for Health Research website (https://www.journalslibrary.nihr.ac.uk)

The level of statistical significance was set at 0·05 (two-sided) for the primary outcomes (see Box 1) and at 0.01 for all

other outcomes. Analyses were carried out in Stata 1313

and REALCOM-impute14

software.

Due to the timelines of recruitment and outcome assessments, there was no opportunity for interim analyses. The Trial

Steering Committee (TSC) maintained assessment of data quality and completion. (Trial registration number =

ISRCTN97000586, Current Controlled Trials).

Process evaluation

Assessment of intervention delivery and process was undertaken using a variety of methods, including: teacher

interviews; parent and child focus groups; headteacher, class teacher and parent questionnaires; teacher logbooks; and

direct observation15

. With the exception of the signposting sheets for which there was no variation in implementation

between schools, a consensus method was used for each of the other three intervention components to allocate

schools a score on a 5-point Likert scale for each dimension of the process evaluation (fidelity/adherence,

reach/dose/exposure, recruitment, quality, and participant responsiveness). Context and programme differentiation

information influence all of these and were therefore also considered throughout this score allocation process. Schools

were then ranked by total score, and grouped to reflect low, medium or high intervention implementation. A detailed

report on the method used to synthesise the WAVES study process evaluation data is being published separately16

.

Role of the funding source

The funder had no role in study design, data collection, data analysis, data interpretation, or writing of the report. The

corresponding author had full access to all the data in the study and had final responsibility for the decision to submit

for publication.

Public involvement

Public involvement was a key feature of the early phases of trial development and feasibility testing prior to this main

trial. Intervention development was informed by detailed consultation with parents, teachers and other school staff.

The intervention was further refined and the process for measuring outcomes tested and adapted by asking children,

parents and teachers about their experiences during the feasibility study. Measures of well-being and body

dissatisfaction were included as outcomes based on their perceived importance among school staff. Our research team

includes an education advisor at the Health Education Service, who has regular contact with schools and advised on

school and participant recruitment.

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Results

Figure 1 shows the flow of schools and pupils during the trial. Among 2,462 eligible pupils from 54 participating schools

at baseline, parental consent for baseline measurements was obtained from 1,467 (59.6%). Recruitment took place

between April and May 2011 (Group 1 schools and pupils) January to May 2012 (Group 2 schools/pupils). Baseline

characteristics are summarised in table 3. Although school characteristics were balanced between groups, there was

baseline imbalance at the pupil level, with children in the control, compared with intervention arm, being more likely to

be male (52.7 vs 49.2%), from generally less deprived households (mean IMD score 37.6 vs 39.8), less likely to be

overweight (mean BMI z-score 0.15 vs 0.23), more likely to consume 5 portions of fruit and vegetables daily (64.8 vs

59.8%) and to achieve at least 60 minutes MVPA daily (49.6 vs 46.4%).

Primary outcomes (Table 4):

At 15 months the mean BMI z-score was non-significantly lower in the intervention compared to the control arm (mean

difference (MD) -0.075 (95% CI -0.183 to 0.033, P=0.175) in baseline adjusted and -0.077 (95% CI -0.191 to 0.037,

P=0.186) in further adjusted models). At 30 months the mean difference was smaller and remained non-significant (MD

-0.027 (95%CI -0.183 to 0.083; P=0.627)).

Secondary outcomes (Table 5):

Anthropometric measurements

In the intervention compared to the control arm, the baseline-adjusted risk difference in the proportion of children who

were overweight or obese was -0.013 (99% CI -0.075 to 0.071, P=0.655) and 0.002 (99% CI -0.068 to 0.093, P=0.948) at

15 and 30 months respectively. The mean difference in sum of skinfolds, waist circumference z-score and body fat

percentage were all non-significant, but slightly favoured the control, compared with the intervention group.

Diet, physical activity and blood pressure

The mean differences in total daily energy intake, physical activity energy expenditure and systolic and diastolic blood

pressures between groups were inconsistent in direction and statistically insignificant at both follow-ups.

Longer term clinical effectiveness

Among Group 1 school participants who were followed up at 39 months, the mean BMI z-score was lower in the

intervention compared with the control arm in the baseline adjusted (MD -0.20; 99% CI -0.46 to 0.05, P=0.037) and

further adjusted models (MD -0.18; -0.39 to 0.03, P=0.030). To investigate why the intervention appeared more

effective at this later time point, we undertook post-hoc analysis to consider whether schools recruited in Group 1

differed from those in Group 2, both in characteristics (appendix, Table A1), and outcomes at earlier time points

(appendix, Table A2). This showed marked baseline adiposity imbalance between arms in Group 2 schools and baseline

differences in ethnicity, deprivation and adiposity between Group 1 and Group 2 schools. There was significant

interaction in the effect of the intervention on the primary outcome between Groups (P=0.001 (FU1) and P=0.020 (FU2)

in the partially adjusted model). Analysis of outcomes by school Group, showed a statistically significantly lower BMI z-

score in the intervention compared with control at first follow up in Group 1 schools (MD –0.23; 95% CI -0.35 to -0.12,

p<0.01 for baseline adjusted model), which was maintained through to third follow up (although no longer statistically

significant at the 1% level). In contrast there was no significant difference between arms at any time point in Group 2

schools (appendix, Table A2).

Harms

Quality of life, as total score or sub-domains, social acceptance or body image dissatisfaction did not differ significantly

between arms at any time. Thus we found no evidence of harm from the intervention.

Sensitivity Analyses

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Sensitivity analyses were all consistent with the main analyses and did not change any conclusions (results not shown).

Process evaluation

Detailed results from the process evaluation are reported separately16

. In brief, the intervention was generally well-

implemented. The scores developed to represent overall programme implementation fidelity (see methods) show that

half the schools achieved at least 75% of the maximum possible score and only three schools failed to achieve at least

65% of that maximum (Figure 2). Teachers found the daily PA intervention component the most challenging to deliver,

with only four schools (17%) achieving high implementation fidelity for that component and 54% of schools allocated to

the low implementation fidelity group. In contrast 46% and 71% of schools achieved high implementation fidelity for

the cooking workshop (CW) andVV components, respectively with classification to the low implementation fidelity

group for 38% (CW) and 21% (VV). However, despite some implementation challenges, the interviews and focus groups

indicated that the programme was often well-received by both teachers17

and also parents and children18

, as illustrated

by the following quotes:

‘it was fantastic and combining the sport and the nutrition was brilliant’ (teacher).

‘There's no doubt about it they've loved it, yeah, ….so it’s been really good for them and that's what it’s all about really

isn't it’ (teacher)

‘it’s good to have it reinforced I think from somebody other than your parents, sometimes if your teacher says it, it’s

true!’ (parent)

‘she’s willing to try more fruits and vegetables, that's what I'm pleased with probably more, before she was quite picky

with what she’d have, but now she is willing to try new things’ (parent)’

‘I teached my mum how to cook it when we cooked in Aston Villa. And I chop a bit at home because I learned how to

chop at Aston Villa’ (child)

‘Because I've done my exercise I can think harder and try’ (child)

Discussion

We found no overall evidence of improvement in the primary outcomes; reduction of BMI-z-scores at 15 and 30

months. However, confidence intervals did not exclude between arm differences in BMI z-score of 0.125, thought to be

clinically important for prevention. The intervention did not have any effects on secondary anthropometric, behavioural

or clinical outcomes, and there were no differential effects in pre-specified subgroups. A clinically significant difference

in BMI-z-score in favour of the intervention was seen in the first cohort of schools recruited who had data available at

39 months. Subsequent post-hoc analysis suggests this may have been a cohort effect, with evidence of effectiveness in

Group 1 schools at all time-points but no effect seen in Group 2 schools at any time point. There was no difference

between groups in terms of the outcomes used to assess harm.

Strengths and weaknesses

The WAVES study is one of the largest childhood obesity prevention trials undertaken to date within a

socioeconomically and ethnically diverse population, with sufficient sample size to assess the primary outcome. Phased

development of the 12-month multicomponent intervention was guided by the MRC framework for complex

interventions9 19

, including a successful feasibility trial10

. It comprised elements identified as promising in systematic

reviews5 6

, and incorporated a range of behaviour change techniques, including those associated with positive

outcomes in previous childhood obesity prevention trials20

. Outcomes were assessed with mainly objective

measurements, using validated instruments and standardised protocols. Loss to follow up was relatively small, with

80% of pupils retained to the second follow up, and loss of one school. A pre-specified analysis plan took account of

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clustering and the findings were robust to a range of sensitivity analyses. This was also one of few trials that undertook

longer term follow up (39 months) to assess sustainability of intervention effects. Comprehensive process evaluation

(described in more detail elsewhere21

) helped to contextualise the findings, and interpret the results16

.

Nevertheless, there were also a number of limitations. Parental consent for study measurements being obtained for

only 60% of eligible children could introduce selection bias, however, a pupil level comparison of demographic

characteristics (gender, ethnicity deprivation) between those with and without consent did not show any major

differences. The balancing algorithm to allocate schools was based on whole school (cluster) level data. However within

clusters, only children from one year group were included and just over half of these consented to study

measurements. There was notable baseline imbalance in the Group 2 cohort (with the intervention arm having greater

adiposity than control), which, despite the use of adjustment methods, may have attenuated the main results.

Statistical adjustment assumes a common linear relationship between covariates and outcome in all clusters, and

misspecification of the model may lead to both under and over adjustment. Baseline imbalance is a known limitation of

cluster trials, and can best be overcome with recruitment of larger numbers of clusters. Although follow up to 30

months was in all groups, longer term follow-up (to 39 months) was limited to a subset of participating schools. The

CADET provided a quick, practical dietary assessment tool with relatively low respondent burden22 23

resulting in

useable data from approximately 85% of children at baseline (81% FU1, 82% FU2). However, dietary intake estimates

may not be reflective of habitual intake, there was a risk of misreporting24

and there may have been seasonal

variation25

between data collection periods. Usable physical activity data was available for 76% at baseline (60%

FU1/52%FU2). These are similar to the rates achieved in other such studies26

.

Comparison with other studies

Our results build on the findings of previous reviews and address limitations in previous childhood obesity prevention

trials. Two systematic reviews suggested that there was moderate6 to strong

5 evidence of effectiveness of school based

interventions in preventing childhood obesity, though intervention heterogeneity, variable design quality and lack of

longer term follow up limit interpretation. A meta-analysis showed that the summary magnitude of effect on BMI z-

score relative to the control was -0.15 units5, which is smaller than the effect size used for estimating sample size in our

trial. Nevertheless, the WAVES study was larger than the 21 previous obesity prevention trials with low risk of bias

included in the meta-analysis (n=9 to 574). Since the publication of the reviews, findings from another UK cluster

randomised controlled trial including over 2000 children from 60 schools are available26

. The trial primarily attempted

to influence activity levels and fruit and vegetable consumption, although it also reported on adiposity outcomes. The

intervention was curriculum based focusing on educational approaches rather than the more experiential skills based

intervention in WAVES. In contrast to our trial, the target population were children at the end of the primary school

years, when rates of obesity have already increased substantially, and included few children from minority ethnic groups

and more deprived areas. Nevertheless, similar to our findings, there was no evidence of an intervention effect on

behavioural or weight outcomes at 12 months.

Interpretation

The balance of components, intensity, and behaviour change strategies used to deliver the intervention may have

contributed to the absence of evidence of effect on the primary outcomes in WAVES and other trials. Although fidelity

of implementation for the WAVES study intervention programme was reasonably high overall, no school delivered all

components completely per protocol and a few schools failed to deliver some or all of the components. In addition, due

to competing demands on teachers, components that required greater teacher input tended to be less well

implemented and this was the main explanation for inter-component differences in fidelity. This suggests that delivery

of a more intensive intervention in a school setting would not be feasible without additional resources. Interventions of

longer duration that are embedded within a whole school setting are likely to be prohibitively costly and complex to

evaluate using clinical trial methodology. Although the findings from the feasibility study suggested the WAVES

intervention was promising, intervention delivery for the trial and subsequent follow up measurements took place

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some years later, during which time wider environmental changes may have diluted any effects. Researcher contact

with schools during the feasibility study was also much greater, but this was not replicable in the definitive trial with a

larger number of schools and would not be implementable outside of a trial setting. Methodological limitations with

baseline imbalance may have also contributed to the observed findings with heterogeneity of effect between schools.

However, even the cohort effect observed in Group 2 schools was small, suggesting that childhood obesity prevention is

unlikely to be achieved by schools alone. Whilst school is an important setting for influencing children’s health

behaviour, and delivery of knowledge and skills to support healthy lifestyles is one of their mandatory functions, wider

influences from the family, community, media and the food industry must also be considered. The qualitative data from

teachers17

and parents18

, collected as part of our process evaluation, support the possibility that these wider influences

have a greater effect than any school based intervention. A metasynthesis of qualitative studies exploring the role of

primary schools in preventing childhood obesity highlighted the need for schools, parents and government to work

together to promote healthy lifestyles in children and support activities in the school setting27

.

In summary, the multicomponent WAVES study intervention which was feasible to deliver and for which there was no

evidence of harm, did not result in significant difference in BMI z-score overall, and there was no evidence of effect on

measured diet or physical activity levels in children. Although wider implementation of this intervention cannot be

recommended for obesity prevention, the lower cost components could be considered by schools to fulfil their

mandated responsibilities for health and wellbeing education. Within the context of the wider evidence, it is likely that

any effect of school based interventions on obesity prevention is small. Several community based interventions

targeting the wider environments have recently also been evaluated, using non-randomised experimental designs.

Whilst a few of these have shown evidence of small effects and lower weight gain in children from intervention

communities28 29

, the findings are not consistent30

and need further evaluation. Even marginal effects may be important

within a wider systems approach to obesity prevention, which incorporates multiple agencies and widespread policy

change to support healthy behaviours.

Authors’ contributions:

All WAVES study Trial Co-investigators contributed to the development of the design for the WAVES study trial and had

contributed to the intervention development as part of the BEACHeS Study. PA wrote the first draft of the paper and all

authors contributed to critical revisions. PA, MP and KKC planned the overall design for the trial. ERL co-ordinated all

aspects of the trial, oversaw data collection, collation and cleaning and contributed to data analysis. She also

contributed to the first draft of the manuscript. EF designed the economic evaluation methods and analysis plan, and

AC undertook the economic analysis and presentation. JJD and KaH contributed to sampling, sample size estimation and

the statistical analysis plan. JM undertook data analysis, supervised by KaH and with support from ERL. UE advised on

physical activity measurements and related methods and oversaw the preparation of the physical activity data. JEC

advised on dietary assessment and related methods and oversaw the CADET data preparation. KiH led data collection

and analysis of dietary data. JLD advised on some of the psychosocial assessment methods. TB, PG and RB advised on

clinical measurement processes. RB and PG advised on aspects related to ethnicity. AD advised on the physical activity

intervention component. SP advised on school recruitment and approaches to keeping schools engaged. EM advised on

the dietary intervention components. JP advised on process evaluation, and TG designed the detailed methods for this.

TG and JLC contributed to data collection and undertook analysis and interpretation of the process evaluation. The final

manuscript was read and approved by all authors.

Acknowledgements:

We thank and acknowledge the children, school staff and parents who participated in the trial, and children, teachers

and parents who took part in interviews and focus groups as part of the process evaluation. We acknowledge the

support of staff at Aston Villa Football Club in delivering the Villa Vitality Programme. We thank the study team,

including Dr Behnoush Mohammadpoor Ahranjani and Mrs Emma Popo who helped in overseeing the study

measurements and data collection, as well as the administrative team who facilitated the running of the project. We

also express our thanks to the research staff who undertook the study measurements and Mr Robert Lancashire who

developed the trial database and oversaw data management.

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Trial Monitoring

The Trial Steering Committee met annually and included:

Chair/ statistician: Dr Kelvin Jordan, Keele University

Subject expert: Professor Peter Whincup, St George’s, University of London

Health economist: Dr Louise Longworth, Brunel University

Public representative: Mr John Bennett, PHSE advisor

Investigators: Prof Peymane Adab, Dr Miranda Pallan, University of Birmingham

Data monitoring committee

Due to the timelines of recruitment and outcome assessments, there was no opportunity for interim analyses, and the

TSC undertook the role of assessment of data quality and completion.

Sponsor and Indemnity

The University of Birmingham holds the relevant insurance policy for this study and acted as the main sponsor.

Department of Health Disclaimer:

The views and opinions expressed therein are those of the authors and do not necessarily reflect those of the HTA,

NIHR, NHS or the Department of Health. The funders have played no role in the design, collection, analysis, and

interpretation of data, nor in the writing of the manuscript and in the decision to submit the manuscript for publication.

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Table 1: Summary of the WAVES Study Intervention Programme

Intervention component Who delivers and details When delivered Intended

participants

Aim 1: Increase children’s physical activity levels

Daily opportunity for additional 30

minutes of MVPA in bouts of >5

minutes.

Class teacher guided through

choice of 4 resources8 to assist in

delivery. Type of activity and timing

of delivery tailored by teacher

according to class circumstances.

Every school day

in Year 2, within

school time (≥15

minutes to be

outside of school

breaks).

Children

Brightly coloured information

sheets: a) signposting local

facilities and opportunities for

family PA outside school b)

including motivational messages

and ideas for being active at home.

Detailed information on

opportunities and facilities for

family based PA in locality,

prepared by researchers in

consultation with school staff,

distributed to families through

school.

Following

randomisation

and term 1 in

Year 2.

Children and

their families

Villa Vitality programme (iconic

sport institution to provide role

model and motivation). Three

sessions over 6 weeks,

interspersed by weekly family

“challenges” and a class project.

Indoor and outdoor sessions led by

Villa community coaches,

highlighted ways in which children

could incorporate PA into their

daily lives.

Family challenges included: pledge

to be active for at least an hour a

day.

Class teacher worked with their

class to develop a song on healthy

lifestyles.

Six-week

programme any

time during Year

2. Coaching

sessions: two half

days at football

ground; one hour

in school.

Children with

family

support for

weekly

challenges

Aim 2: Improve children’s dietary intake

Cooking skills workshops to

increase knowledge and equip

families with skills to prepare

healthier food (increase fruit,

vegetable and fibre intake, and

reduce fat and sugar intake).

Teacher provided with training and

resources to deliver workshops and

2 to 3 short lessons on healthy

eating prior to each workshop.

Parents invited to accompany

children during workshops, led by

teachers, where they practised

skills (e.g. chopping, grating,

peeling, mixing) to prepare a meal.

Written information sent home

following each session.

Three workshops

(breakfast,

lunch/snacks,

evening meal);

one each term

during Year 2.

Children and

parents

Villa Vitality programme (iconic

sport institution to provide role

model and motivation). Two

sessions over 6 weeks,

interspersed by weekly family

“challenges” and a class project.

Sessions designed to re-enforce

healthy eating messages and skills

from cooking workshops.

Villa community staff provided

interactive sessions on healthy

eating and supervised practical

preparation of a healthy meal over

the two stadium visit days (6-

weeks apart).

Family challenges : swap a snack,

drink more water, eat a healthy

breakfast every day , eat 5 portions

of fruit and veg every day and cook

a healthy family meal.

Class teacher worked with their

class to develop a song on healthy

lifestyles.

Six-week

programme any

time during Year

2, with two half

day sessions at

football ground.

Children with

family

support for

weekly

challenges

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Box 1: Primary and secondary outcome measures for the WAVES study

Primary outcomes

- Body mass index (BMI) z-scores, derived from researcher measured height and weight, and using UK 1990 BMI

reference curves for children31

, at 15 and 30 months (for clinical effectiveness).

- Cost per Quality-Adjusted Life Year (QALY) (derived from child reported Child Health Utility 9D32

) at 30 months (for

the cost-effectiveness analysis) – Not reported here

Secondary outcomes (all assessed at 15 and 30 months except outcome 6)

1. Anthropometric measurements:

i) Overweight / obesity (BMI ≥85th percentile / ≥95th

percentile on UK 1990 centile charts for boys and girls)

ii) Sum of four skinfolds* (biceps, triceps, suprailiac and subscapular) measured by researchers

iii) Waist circumference z-score, derived from researcher measured waist circumference using UK 1990 growth

reference curves for children31

iv) Body fat percentage, assessed using bioelectrical impedance technology

2. Dietary daily total energy intake (kJ in 24 hours), fat, sugar, fibre (g/day) and fruit and vegetable intake (g/day and

portions), obtained using a validated questionnaire22

3. Daily physical activity energy expenditure (kJ/kg body weight/day), and time spent being sedentary and undertaking

at least moderate intensity activity (min/24 hours) assessed by Actiheart

4. Blood pressure, measured by researchers

5. Psychosocial outcomes (harm): Self-reported health related quality of life (using validated PedsQL), social

acceptance, and self-reported body image dissatisfaction (score derived from sex-specific 7-point Child’s Body

Image Scale)

6. Longer term clinical effectiveness (BMI z-scores) at 39 months post-baseline measures in Group 1 schools

* Skinfold thickness was measured at 5 different sites (biceps, triceps, thigh, suprailiac and subscapular), as detailed in the protocol.

However, compared to the other sites, the children found the measurement of thigh skinfold thickness more intrusive resulting in a

lower level of data availability for this compared to the other sites. The skinfold thickness summary measure was therefore

calculated excluding the thigh measurement.

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Table2: Summary of measurements undertaken within the WAVES study

Measurement Instrument Number of measures Method of assessment

Measurement by trained research staff using standard protocols

Weight

Body fat %

Tanita bioimpedance

monitor (Tanita SC-

331S; Tanita

Corporation., Tokyo,

Japan)

Once Barefoot and in light

clothing

Height Leicester Height

Measure Twice (third measure if

difference >0.4cm)

Barefoot and in light

clothing

Waist circumference

(to nearest 0.1 cm)

Flexible, non-stretch,

cloth tape measure

Skinfold thickness

(biceps, triceps,

subscapular, suprailiac

and thigh)

Holtain Tanner /

Whitehouse Skinfold

Caliper (Holtain Ltd.,

UK)

Twice (third measure if

difference >0.4mm)

Measured on non-

dominant side

Dietary intake Child And Diet

Evaluation Tool

(CADET) (115-item 24-

hour food tick list22

completed for 7

distinct time periods)

Once (24 hours) Completed by trained

researchers in school,

and parent/carer at

home (with

instructional DVD)

Physical activity energy

expenditure

Actiheart

(Cambridge

Neurotechnology Ltd,

Papworth, UK)

Once (worn

continuously for 5

days, including a

weekend)

Fitted in school by

trained researcher

Blood pressure Automated

oscillometric monitor

(BpTRU BPM-100,

British Columbia,

Canada)

Twice (third measure if

error reading, or if one

value outside

normal range)

3 minutes seated-rest

before and between

readings

Quality of life Pediatric Quality of Life

Inventory (PedsQL)

Once

Researcher

administered

questionnaire

Social

acceptance

Kidscreen-52 health

questionnaire for

children and young

people

Body image

dissatisfaction

Child's Body Image

Scale (CBIS)

Preference-based

utility

Child Health Utility 9D

(CHU9D)

Demographic data

(date of birth, sex,

ethnicity, postcode

[proxy measure for

deprivation])

Parent questionnaires Assessment at baseline Parent report and

school records

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Figure 1: WAVES Study trial profile

*Baseline measurements were not obtained for 75 consented children because they: were absent on the measurement day (n=64); had left the

school (n=6); did not assent to height and/or weight measurements (n=3). Pupils without consent, compared to those with parental consent, were

more likely to be from minority ethnic groups (40.8% and 30.5% respectively South Asian, 9.1% and 7.9% respectively Black African Caribbean) and

from more deprived households (66.2% vs 54.9% from most deprived quintile). Over the course of the trial, one school (intervention; 20 consented

pupils) withdrew before the first follow up, and an additional 160 children (76 intervention, 84 control) were lost at first, and a further 118 (64

intervention, 54 control) at the second follow-up. Loss to follow-up was mainly due to pupils moving schools (83% and 77% of losses at first and

second follow-up), whilst the remainder were due to parental withdrawal of consent. For the primary outcome, complete data from 53 schools

were available for 1,249 children at first follow up, and 1145 at the second follow up, which was greater than the estimated sample size

requirement. At third follow up, data on primary outcome were available for 488 children from 27 Group 1 schools. For other outcomes, data

availability varied, and the numbers included for each analysis are shown in the tables.

*

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Table 3: Baseline characteristics of school pupils participating in the WAVES study overall and by trial arm

Characteristic N (number pupils in intervention arm) INTERVENTION

ARM

CONTROL ARM

TOTAL

Demographic

Age (years), mean (SD)

N=1397 (662), Not known: Intervention=27, Control= 43 6.31 (0.30) 6.27 (0.31) 6.29 (0.31)

Gender, n (%)

N=1467 (689)

Male 339 (49.2) 410 (52.7) 749 (51.1)

Female 350 (50.8) 368 (47.3) 718 (48.9)

Ethnicity, n (%)

N=1451 (676)

White British 297 (43.9) 361 (46.6) 658 (45.3)

South Asian 221 (32.7) 222 (28.6) 443 (30.5)

Black African Caribbean 62 ( 9.2) 53 ( 6.8) 115 ( 7.9)

Other 96 (14.2) 139 (17.9) 235 (16.2)

Not known 13~ 3~ 16~

IMD quintile, n (%)

N=1439 (670)

1 (most deprived) 392 (58.5) 398 (51.8) 790 (54.9)

2 120 (17.9) 154 (20.0) 274 (19.0)

3 72 (10.7) 74 ( 9.6) 146 (10.1)

4 65 ( 9.7) 54 ( 7.0) 119 ( 8.3)

5 (least deprived) 21 ( 3.1) 89 (11.6) 110 ( 7.6)

Not known 19~ 9~ 28~

IMD score, median [IQR]

N=1439 (670), Not known: Intervention=19, Control= 9

39.80

[21.86 - 52.68]

37.60

[17.89 - 48.79]

38.93

[20.14 - 49.49]

Anthropometric

BMI z-score, mean (SD)


Height (cm), mean (SD)


Waist circumference, z-score mean (SD)


Sum of 4 skinfolds* (mm), median [IQR]

N=1137 (540),Not known: Intervention=149, Control= 181

28.55

[23.30 – 35.43]

28.10

[23.00 – 36.60]

28.35

[23.10 – 36.05]

Body fat %, mean (SD)

N=1376 (660),Not known: Intervention=29, Control= 62 21.30 (5.35) 20.95 (5.22) 21.12 (5.28)

Weight status#, n (%)

N=1392 (660)

Underweight (≤ 2nd

centile) 20 ( 3.0) 20 ( 2.7) 40 ( 2.9)

Healthy weight (>2nd

and <85th

centiles) 495 (75.0) 562 (76.8) 1057 (75.9)

Overweight (≥85th

and <95th

centiles) 61 ( 9.2) 63 ( 8.6) 124 ( 8.9)

Obese (≥95th

centile) 84 (12.7) 87 (11.9) 171 (12.3)

Not known 29~ 46~ 75~

24 hour dietary intake

Energy (kj in 24 hours), median [IQR]


6904

[5865 – 8054]

6911

[5804 – 7964]

6907

[5829 – 8002]

≥ 5 portions of fruit and veg, n (%)

N=1187 (562)

Yes 336 (59.8) 405 (64.8) 741 (62.4)

No 226 (40.2) 220 (35.2) 446 (37.6)

Not known 127~ 153~ 280~

Physical activity

Physical activity energy expenditure (kJ/kg/day), mean (SD)

N= 1052 (492), Not known: Intervention=197, Control= 218 96.43 (23.16) 94.08 (24.38) 95.18 (23.83)

≥ 60 mins MVPA/24 hours, n (%)

N=1048 (491),

Yes 228 (46.4) 276 (49.6) 504 (48.1)

No 263 (53.6) 281 (50.4) 544 (51.9)

Not known 198~ 221~ 419~

Psychological

PedsQL total score, median [IQR]


71.74

[60.87 - 82.61]

73.91

[60.87 - 82.61]

71.74

[60.87 - 82.61)

~not included in denominator for calculation of percentages

*subscapular skinfold + suprailiac skinfold + biceps skinfold + triceps skinfold #based on UK 1990 reference centile curves and applying the cut-offs used for population monitoring

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Confidential: For Review Only18

Table 4: Adjusted differences for BMI z-score between control and intervention groups at first, second and third follow up

Follow up

time point

N = total participants

(n = number in intervention arm)

BMI z-score

Mean (SD) Mean Difference p value

(95% CI)

Intervention arm

BL all participants 0.23 (1.24)

BL G1 participants only 0.29 (1.24)

Control arm

BL all participants 0.15 (1.20)

BL G1 participants only 0.28 (1.12)

Intervention vs control

(Baseline adjusted)a


(further adjusted)b

15 months N=1197* (n=556) BL adjusted

0.34 (1.34) 0.23 (1.27) -0.075

(-0.183 to 0.033)

0.175 -0.077

(-0.191 to 0.037)

0.186

N=837* (n=393) further adjusted

30 months N=1094* (n=505) BL adjusted

0.42 (1.34) 0.31 (1.32) -0.027

(-0.137 to 0.083)

0.627 -0.042

(-0.163 to 0.080)

0.500

N=772* (n=359) further adjusted

39 months

N=467# (n=232) BL adjusted

N=345# (n=173) further adjusted 0.49 (1.37) 0.63 (1.22)

-0.204

(-0.396 to -0.013)

0.037 -0.177

(-0.386 to 0.033)

0.030

(99%CI -0.456 to 0.048) (99%CI -0.386 to 0.033)

SD: Standard deviation. CI: Confidence interval. BL: baseline. G1: Group 1 school. *: Includes group 1 and group 2 school participants.#: Includes group 1 school participants only.

a: Adjusted for

baseline outcome. b: Adjusted for baseline outcome, baseline pupil level covariates: (sex, ethnicity , deprivation (IMD score for home postcode), 24 hour total energy intake, physical activity energy

expenditure) and baseline school level covariates (size (number of pupils on roll), % school population South Asian, % school population Black African Caribbean, % free school meal eligibility)

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Table 5: Adjusted differences for secondary outcomes (anthropometric, diet, physical activity and psychosocial) between control and intervention arm at first

and second follow up

Follow up outcome variable

Intervention arm Control arm Intervention vs control



(further adjusted)b

N FU1/N FU2= total participants (n= BL FU1 FU2 BL FU1 FU2 FU1 FU2 FU1 FU2

number in intervention arm)

Mean (SD) / Median [IQR] / N {%} Mean (SD) / Median [IQR] / N {%}

MD(99 % CI) p

value

or

RD{99% CI} p value

MD(99% CI) p value

or

RD{99% CI} p value

MD(99% CI) p value

or

RD{99% CI} p value

MD(99% CI) p value

or

RD{99% CI} p value

Obese

N FU1 = 1197 (n = 556 (BL adjusted))

837 (n = 393 (further adjusted)

N FU2 = 1094 (n = 505 (BL adjusted))

772 (n = 359 (further adjusted))

84

{12.73}

93

{16.20}

108

{20.61}

87

{11.89}

100

{14.81}

112

{18.04}

-0.036

{-0.073 to

0.019}

0.074 -0.004

{-0.050 to

0.057}

0.837 -0.007

{-0.046 to

0.045}

0.676 0.020

{-0.030 to

0.086}

0.336

Obese/Overweightc

N FU1 = 1197 (n = 556 (BL adjusted))


N FU2 = 1094 (n = 505 (BL adjusted))


145

{21.97}

165

{28.75}

176

{33.59}

150

{20.49}

167

{24.74}

-0.013

{-0.075 to

0.071}

0.655 0.002

{-0.068 to

0.093}

0.948 0.000

{-0.064 to

0.087}

0.994 0.004

{-0.062 to

0.087}

0.892

Sum of 4 skinfold (mm)d e

N FU1 = 902 (n = 421 (BL adjusted))




28.55

[23.30 –

35.43]

31.48

[24.57 –

43.65]

34.70

[25.5 –

49.95]

28.10

[23.00 –

36.60]

29.40

[23.63 –

41.67]

31.93

[24.00 –

48.90]

0.366

(-0.322 to

1.054)

0.170 0.644

(-0.067 to

1.356)

0.020 0.417

(-0.384 to

1.219)

0.180 0.532

(-0.268 to

1.333)

0.087

Waist z-score

N FU1 = 1069 (n = 490 (BL adjusted))




0.77

(1.24)

1.05

(1.36)

1.15

(1.25)

0.66

(1.25)

0.87

(1.32)

0.90

(1.35)

0.026

(-0.229 to

0.281)

0.794 0.103

(-0.087 to

0.293)

0.163 0.019

(-0.166 to

0.205)

0.789 0.068

(-0.133 to

0.269)

0.383

Body fat %

N FU1 = 1169 (n = 553 (BL adjusted))


N FU2 = 1051 (n = 495 (BL adjusted))


21.30

(5.35)

21.79

(6.73)

22.52

(7.48)

20.95

(5.22)

20.87

(6.30)

21.58

(7.26)

0.040

(-0.942 to

1.021)

0.917 0.344

(-0.629 to

1.317)

0.362 0.048

(-0.999 to

1.095)

0.906 0.166

(-0.992 to

1.324)

0.712

Energy intake (kj in 24 hours)f




6904

[5865 –

8054]

7152

[6107 –

8376]

7656

[6436 –

9118]

6911

[5804 –

7964]

7074

[5963 –

8233]

7817

[6748 –

9212]

61.531

(-305.536 to

428.597)

0.666 -139.552

(-570.798 to

291.693)

0.405 30.988

(-348.629 to

410.604)

0.833 -273.658

(-724.284 to

176.967)

0.118

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Fat intake (g in 24 hours)f





56.08

[45.39 –

69.28]

60.95

[47.32 –

71.98]

65.66

[51.81 –

79.88]

54.74

[44.75 –

67.58]

57.36

[46.87 –

70.15]

67.41

[54.59 –

81.08]

1.426

(-2.291 to

5.143)

0.323 -1.943

(-6.629 to

2.742)

0.285 1.260

(-2.336 to

4.857)

0.367 -2.740

(-7.652 to

2.171)

0.151

Free sugars intake (g in 24 hours)





76.63

(31.01)

72.05

(33.03)

74.50

(32.18)

76.13

(30.88)

75.31

(32.88)

81.21

(35.16)

-4.329

(-12.781 to

4.124)

0.187 -7.886

(-18.488 to

2.716)

0.055 -5.636

(-12.285 to

1.014)

0.029 -9.220

(-19.032 to

0.592)

0.015

Fibre intake (g in 24 hours)f





11.00

[8.80 –

13.68]

11.76

[9.41 –

14.62]

12.44

[10.01 –

15.47]

11.35

[8.99 –

13.95]

11.77

[9.18 –

14.46]

12.77

[10.44 –

15.66]

0.013

(-0.767 to

0.793)

0.965 -0.163

(-1.162 to

0.837)

0.675 0.008

(-0.914 to

0.930)

0.982 -0.461

(-1.499 to

0.577)

0.253

Fruit and vegetable intake (g in 24 hours)g





226.92

[132.00 –

330.09]

200.23

[91.79 –

315.28]

218.06

[115.60 –

348.41]

247.58

[157.25 –

341.40]

201.84

[116.16 –

316.56]

219.28

[116.54 –

341.33]

-2.875

(-33.148 to

27.399)

0.807 14.195

(-29.969 to

58.360)

0.408 -5.652

(-41.150 to

29.847)

0.682 14.598

(-34.821 to

64.018)

0.447

≥ 5 portions of fruit and vegetablesh





336

{59.79}

244

{48.13}

253

{55.85}

405

{64.80}

297

{49.09}

317

{56.41}

-0.014

{-0.111 to

0.109}

0.753 0.012

{-0.090 to

0.135}

0.789 0.004

{-0.075 to

0.098}

0.900 0.002

{-0.096 to

0.122}

0.954

PA energy expenditure (kj/kg/day)





96.43

(23.16)

91.70

(23.71)

79.66

(22.26)

94.08

(24.38)

91.27

(25.42)

78.60

(22.43)

-0.866

(-6.811 to

5.079)

0.708 0.001

(-5.745 to

5.747)

0.999 -1.762

(-7.007 to

3.482)

0.387 -0.224

(-5.344 to

4.896)

0.910

Sedentary time (hours/24 hours)



N FU2 = 575 (n = 2544 (BL adjusted))


14.42

(1.88)

14.01

(2.12)

15.86

(1.86)

14.57

(1.78)

14.08

(2.20)

15.73

(1.94)

-0.045

(-0.610 to

0.521)

0.839 0.186

(-0.443 to

0.814)

0.447 0.156

(-0.384 to

0.697)

0.456 0.287

(-0.368 to

0.941)

0.260

MVPA time (minutes/24 hours)f




57.91

[42.52 –

85.90]

62.07

[38.80 –

102.97]

40.79

[31.47 –

57.19]

59.47

[42.80 –

81.53]

59.80

[40.91 –

96.95]

44.36

[32.85 –

67.94]

-1.310

(-11.843 to

9.224)

0.749 -3.332

(-10.706 to

4.042)

0.245 -3.939

(-16.561 to

8.682)

0.421 -4.314

(-12.697 to

4.070)

0.185

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Achieving >= 60 minutes MVPA in 24 hoursi





228

{46.44}

207

{52.27}

70

{22.80}

276

{49.55}

234

{49.79}

120

{30.53}

0.041

{-0.085 to

0.207}

0.446 -0.068

{-0.166 to

0.096}

0.215 0.005

{-0.101 to

0.140}

0.911 -0.067

{-0.165 to

0.096}

0.219

Systolic blood pressure (mmHg)

N FU1 = 1100 (n = 513 (BL adjusted))




95.67

(9.04)

95.35

(8.78)

96.98

(8.30)

98.10

(10.06)

95.29

(8.22)

97.75

(8.21)

0.624

(-1725 to

2.973)

0.494 0.310

(-1.528 to

2.148)

0.664 0.931

(-1.307 to

3.169)

0.284 0.577

(-1.431 to

2.584)

0.459

Diastolic blood pressure (mmHg)

N FU1 = 1100 (n = 513 (BL adjusted))




62.18

(7.99)

62.08

(7.81)

63.29

(7.46)

64.21

(8.59)

62.19

(7.43)

63.50

(7.34)

0.335

(-1.721 to

2.392)

0.675 0.482

(-1.570 to

2.533)

0.545 0.945

(-1.247 to

3.137)

0.267 0.517

(-1.605 to

2.639)

0.530

PedsQL total scorej

N FU1 = 1171 (n = 538 (BL adjusted))


N FU2 = 1055 (n = 477 (BL adjusted))


71.74

[60.87 –

82.61]

76.09

[65.22 –

84.78]

82.61

[71.74 –

89.13]

73.91

[60.87 –

82.61]

76.09

[65.22 –

84.78]

80.43

[71.74 –

89.13]

-0.630

(-4.385 to

3.124)

0.665 1.248

(-2.301 to

4.796)

0.365 -0.437

(-4.271 to

3.398)

0.769 1.246

(-1.815 to

4.307)

0.294

PedsQL physical functioning score

N FU1 = 1171 (n = 538 (BL adjusted))


N FU2 = 1056 (n = 476 (BL adjusted))


73.06

(18.07)

77.79

(16.28)

83.71

(13.86)

74.87

(17.26)

78.86

(15.14)

84.18

(12.85)

-0.649

(-4.006 to

2.708)

0.618 0.118

(-3.411 to

3.646)

0.932 -0.191

(-3.498 to

3.116)

0.882 0.704

(-2.557 to

3.965)

0.578

PedsQL psychosocial functioning score

N FU1 = 1170 (n = 538 (BL adjusted))


N FU2 = 1054 (n = 476 (BL adjusted))


69.47

(17.95)

71.27

(16.58)

77.52

(14.40)

69.28

(18.19)

72.10

(15.81)

76.27

(14.96)

-0.661

(-3.798 to

2.475)

0.587 1.593

(-1.598 to

4.784)

0.198 -0.679

(-3.352 to

1.993)

0.513 1.468

(-1.480 to

4.415)

0.200

PedsQL emotional functioning score

N FU1 = 1171 (n = 538 (BL adjusted))


N FU2 = 1055 (n = 477 (BL adjusted))


73.36

(22.20)

75.88

(21.02)

83.42

(18.11)

71.68

(23.05)

75.75

(20.67)

81.57

(18.86)

-0.045

(-4.236 to

4.147)

0.978 1.972

(-1.766 to

5.710)

0.174 0.115

(-3.954 to

4.184)

0.942 2.021

(-1.745 to

5.787)

0.167

PedsQL social functioning score

N FU1 = 1169 (n = 537 (BL adjusted))


N FU2 = 1053 (n = 475 (BL adjusted))

67.72

(22.34)

70.89

(20.52)

76.72

(18.31)

68.60

(21.71)

72.39

(19.39)

75.81

(18.91)

-1.134

(-4.634 to

2.366)

0.404 0.993

(-2.517 to

4.503)

0.466 -1.137

(-4.193 to

1.918)

0.338 1.089

(-2.305 to

4.483)

0.409

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PedsQL school functioning score

N FU1 = 1167 (n = 538 (BL adjusted))


N FU2 = 1052 (n = 475 (BL adjusted))


67.35

(21.72)

67.04

(20.03)

72.40

(17.50)

67.54

(21.56)

68.07

(18.72)

71.42

(18.21)

-0.810

(-4.533 to

2.912

0.575 1.698

(-2.181 to

5.557)

0.260 -0.876

(-4.331 to

2.579)

0.514 1.447

(-2.077 to

4.971

0.290

Kidscreen-52 bullying

N FU1 = 1156 (n = 533 (BL adjusted))


N FU2 = 1047 (n = 475 (BL adjusted))


11.74

(3.20)

13.21

(6.95)

14.30

(7.92)

12.05

(2.97)

14.22

(10.14)

14.05

(6.28)

-1.101

(-2.655 to

0.453)

0.068 0.594

(-0.482 to

1.671)

0.155 -0.544

(-1.930 to

0.842)

0.312 0.359

(-0.799 to

1.516)

0.425

Body image satisfaction score

N FU1 = 1149 (n = 533 (BL adjusted))


N FU2 = 1044 (n = 476 (BL adjusted))


1.54

(1.39)

1.37

(1.17)

1.19

(1.04)

1.56

(1.40)

1.27

(1.11)

1.11

(0.96)

0.041

(-0.168 to

0.251)

0.611 0.049

(-0.132 to

0.229)

0.487 0.015

(-0.168 to

0.216)

0.847 -0.024

(-0.185 to

0.137)

0.700

BL: baseline. FU1: follow up 1. FU2: follow up 2. SD: standard deviation. IQR: interquartile range. MD: mean difference. CI: confidence interval. RD: risk difference. PA: physical activity. a: adjusted for

baseline outcome. b: adjusted for baseline outcome, baseline pupil level covariates: (sex, ethnicity , deprivation (IMD score for home postcode), 24 hour total energy intake, physical activity energy

expenditure) and baseline school level covariates (size (number of pupils on roll), % school population South Asian, % school population Black African Caribbean, % free school meal eligibility). c:

adjusted for baseline BMI z-score. d: Transformed via Inverse. e: Sum of four skinfolds included summation of biceps, subscapular, suprailiac, and triceps. f: Transformed via natural logarithm. g:

Transformed via square root. h: Adjusted for total grams of fruit and vegetables consumed in 24 hours. i: Adjusted for minutes of MVPA per 24 hours. j: Transformed via squaring. k: 95% rather than

99% CIs presented for this variable as this was one of the primary outcomes

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Figure 2: Summary of findings from process evaluation measures overall and across intervention components, by school

School

Intervention component TOTAL

SCORE* Physical

Activity

Cooking

Workshops

Villa

Vitality

1 68

2 68

3 67

4 64

5 62

6 61

7 60

8 60

9 58

10 58

11 57

12 57

13 55

14 54

15 53

16 52

17 51

18 51

19 51

20 51

21 49

22 42

23 39

24 35

25 0

26 0

*Maximum = 75

Implementation fidelity level = low = medium = high

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24

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Appendix: Table A1 - Baseline characteristics of intervention and control arm participants in Group 1 and Group 2 Schools

Group 1 schools ( recruited 2011; n=650) Group 2 schools (recruited 2012; n=817)

Characteristic INTERVENTION

ARM

CONTROL ARM

TOTAL INTERVENTION

ARM

CONTROL ARM

TOTAL

Demographic

Age (years) mean (SD) 6.34 (0.30) 6.32 (0.30) 6.33 (0.30) 6.28 (0.30) 6.22 (0.31) 6.25 (0.31)

Gender, n (%)

Male 137 (45.4) 180 (51.7) 202 (52.2) 230 (53.5) 432 (52.9) 317 (48.8)

Female 165 (54.6) 168 (48.3) 185 (47.8) 200 (46.5) 385 (47.1) 333 (51.2)

Ethnicity, n (%)

White British 154 (51.7) 181 (52.2) 143 (37.8) 180 (42.1) 323 (40.1) 335 (51.9)

South Asian 82 (27.5) 83 (23.9) 139 (36.8) 139 (32.5) 278 (34.5) 165 (25.6)

Black African Caribbean 25 ( 8.4) 23 ( 6.6) 37 ( 9.8) 30 ( 7.0) 67 ( 8.3) 48 ( 7.4)

Other 37 (12.4) 60 (17.3) 59 (15.6) 79 (18.5) 138 (17.1) 97 (15.0)

IMD quintile, n (%) 1 (most deprived) 128 (44.0) 179 (51.9) 264 (69.7) 219 (51.7) 483 (60.1) 307 (48.3)

2 67 (23.0) 73 (21.2) 53 (14.0) 81 (19.1) 134 (16.7) 140 (22.0)

3 48 (16.5) 35 (10.1) 24 ( 6.3) 39 ( 9.2) 63 ( 7.8) 83 (13.1)

4 44 (15.1) 25 ( 7.2) 21 ( 5.5) 29 ( 6.8) 50 ( 6.2) 69 (10.8)

5 (least deprived) 4 ( 1.4) 33 ( 9.6) 17 ( 4.5) 56 (13.2) 73 ( 9.1) 37 ( 5.8)

IMD score, median [IQR] 30.25

[17.14 - 44.36]

37.55

[19.84 – 46.29]

32.87

[17.59 – 46.09]

42.75

[30.92 – 55.24]

37.88

[16.42 – 50.46]

41.63

[22.69 – 51.65]

Anthropometric

BMI z-score, mean (SD) 0.29 (1.24) 0.28 (1.12) 0.29 (1.18) 0.19 (1.24) 0.04 (1.26) 0.11 (1.25)

Waist circumference z-score, mean (SD) 0.86 (1.17) 0.92 (1.14) 0.89 (1.16) 0.69 (1.30) 0.41 (1.29) 0.54 (1.30)

Sum of 4 skinfolds* (mm), median [IQR] 29.03

[24.48– 35.65]

30.55

[24.45– 40.10]

29.68

[24.48 – 37.93]

27.55

[22.13– 35.30]

26.75

[22.15– 34.05]

27.20

[22.15 – 34.85]

Body fat %, mean (SD) 21.33 (5.19) 21.18 (5.21) 21.25 (5.20) 21.27 (5.49) 20.76 (5.22) 21.01 (5.35)

Weight status#, n (%) Underweight (≤ 2

nd centile) 8 ( 2.7) 2 ( 0.6) 12 ( 3.3) 18 ( 4.4) 30 ( 3.9) 10 ( 1.6)

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Healthy weight (>2nd

, <85th

centiles) 217 (74.3) 258 (78.9) 278 (75.5) 304 (75.1) 582 (75.3) 475 (76.7)

Overweight (≥85th

, <95th

centiles) 28 ( 9.6) 24 ( 7.3) 33 ( 9.0) 39 ( 9.6) 72 ( 9.3) 52 ( 8.4)

Obese (≥95th

centile) 39 (13.4) 43 (13.1) 45 (12.2) 44 (10.9) 89 (11.5) 82 (13.2)

24 hour dietary intake

Energy (kj in 24 hours), median [IQR] 6907

[5858 – 7964]

7071

[5960 – 8030]

7015

[5900 – 8009]

6894

[5871 – 8098]

6739

[5700 – 7830]

6833

[5779 – 7988]

≥ 5 portions of fruit and veg,

n (%)

Yes 160 (60.6) 207 (72.1) 176 (59.1) 198 (58.6) 374 (58.8) 367 (66.6)

No 104 (39.4) 80 (27.9) 122 (40.9) 140 (41.4) 262 (41.2) 184 (33.4)

Physical activity

Physical activity energy expenditure (kJ/kg/day), mean (SD) 93.07 (21.69) 91.82 (22.42) 92.39 (22.07) 99.73 (24.11) 91.81 (22.42) 97.98 (25.20)

≥ 60 mins MVPA/24 hours,

n (%)

Yes 88 (36.4) 133 (47.0) 140 (56.2) 143 (52.2) 283 (54.1) 221 (42.1)

No 154 (63.6) 150 (53.0) 109 (43.8) 131 (47.8) 240 (45.9) 304 (57.9)

Psychological

PedsQL total score, median [IQR] 72.83

[63.04 – 84.78]

73.91

[63.04 - 82.61]

73.91

[63.04 - 82.61

69.57

[56.52 – 80.43]

71.74

[60.87 - 82.61]

71.74

[58.70 – 80.43]

CHU9D utility score, mean (SD) 0.84 (0.13) 0.82 (0.14) 0.83 (0.14) 0.83 (0.14) 0.81 (0.15) 0.82 (0.14)

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Table A2: Adjusted differences for BMI z-score between control and intervention groups at each follow up for Group 1 and Group 2 schools

Follow

up time

point

N = total participants

(n = in intervention arm)

BMI z-score

Mean (SD) Mean Difference p value

(95% CI)

Intervention arm

BL G1 participants 0.29 (1.24)


Control arm






(further adjusted)b

15

months

Group 1 N=536 (n=258) BL adjusted

N=407 (n=195) further adjusted 0.35 (1.32) 0.53 (1.16)

-0.23 (-0.35 to -0.12)

P<0.001

-0.26 (-0.36 to -0.16)

P<0.001


N=430 (n=198) further adjusted 0.33 (1.35) -0.00 (1.31)

0.08 (-0.09 to 0.25)

P=0.35

0.14 (-0.03 to 030)

P=0.10

30

months



-0.17 (-0.34 to 0.00)

P=0.06

-0.18 (-0.35 to -0.01)

P=0.04



0.09 (-0.04 to 0.22)

P=0.17

0.11 (-0.01 to 0.23)

P=0.08

39

months


N=345 (n=173) further adjusted

0.49 (1.37) 0.63 (1.22) -0.20 (-0.46 to 0.05)

P=0.04

-0.18 (-0.39 to 0.03)

P=0.03

Group 2 NA NA NA NA NA

SD: Standard deviation. CI: Confidence interval. BL: baseline. G1: Group 1 school. NA: not applicable. a: Adjusted for baseline outcome.

b: Adjusted for baseline outcome, baseline pupil level

covariates: (sex, ethnicity , deprivation (IMD score for home postcode), 24 hour total energy intake, physical activity energy expenditure) and baseline school level covariates (size (number of

pupils on roll), % school population South Asian, % school population Black African Caribbean, % free school meal eligibility

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29

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BMC Public HealthBMC Public Health

This Provisional PDF corresponds to the article as it appeared upon acceptance. Fully formattedPDF and full text (HTML) versions will be made available soon.

A cluster-randomised controlled trial to assess the effectiveness and cost-effectiveness of a childhood obesity prevention programme delivered through

schools, targeting 6–7 year old children: the WAVES study protocol

BMC Public Health Sample

doi:10.1186/s12889-015-1800-8

Peymane Adab ([email protected])Miranda J Pallan ([email protected])

Emma R Lancashire ([email protected])Karla Hemming ([email protected])

Emma Frew ([email protected])Tania Griffin ([email protected])

Timothy Barrett ([email protected])Raj Bhopal ([email protected])

Janet E Cade ([email protected])Amanda Daley ([email protected])

Jonathan Deeks ([email protected])Joan Duda ([email protected])

Ulf Ekelund ([email protected])Paramjit Gill ([email protected])

Eleanor McGee ([email protected])Jayne Parry ([email protected])

Sandra Passmore ([email protected])Kar Keung Cheng ([email protected])

Sample

ISSN 1471-2458

Article type Study protocol

Submission date 16 April 2015

Acceptance date 24 April 2015

Article URL http://dx.doi.org/10.1186/s12889-015-1800-8

For information about publishing your research in BioMed Central journals, go tohttp://www.biomedcentral.com/info/authors/

© 2015 Adab et al. ; licensee BioMed CentralThis is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), whichpermits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain

Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

(2015) 15:488

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http://dx.doi.org/10.1186/s12889-015-1800-8

http://www.biomedcentral.com/info/authors/

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http://creativecommons.org/publicdomain/zero/1.0/

Confidential: For Review OnlyA cluster-randomised controlled trial to assess the

effectiveness and cost-effectiveness of a childhood

obesity prevention programme delivered through

schools, targeting 6–7 year old children: the WAVES

study protocol

Peymane Adab1*

* Corresponding author

Email: [email protected]

Miranda J Pallan1


Emma R Lancashire1*

* Corresponding author


Karla Hemming1


Emma Frew1


Tania Griffin1


Timothy Barrett2


Raj Bhopal3


Janet E Cade4


Amanda Daley1


Jonathan Deeks1


Joan Duda5


Ulf Ekelund6,7


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Confidential: For Review OnlyParamjit Gill

1


Eleanor McGee8


Jayne Parry1


Sandra Passmore9


Kar Keung Cheng1


1 Health & Population Sciences, University of Birmingham, B15 2TT

Birmingham, UK

2 School of Clinical and Experimental Medicine, University of Birmingham,

Birmingham, UK

3 Edinburgh Migration, Ethnicity and Health Research Group, Usher Institute of

Population Health Sciences and Informatics, The University of Edinburgh,

Edinburgh, Scotland

4 Food Science and Nutrition, University of Leeds, Leeds, UK

5 School of Sport, Exercise and Rehabilitation Sciences, University of

Birmingham, Birmingham, UK

6 Cambridge MRC Epidemiology Unit, Cambridge, UK

7 Norwegian School of Sport Sciences, Oslo, Norway

8 Birmingham Community Healthcare NHS Trust, Birmingham, UK

9 Services for Education, Birmingham, UK

Abstract

Background

There is some evidence that school-based interventions are effective in preventing childhood

obesity. However, longer term outcomes, equity of effects and cost-effectiveness of

interventions have not been assessed.

The aim of this trial is to assess the clinical and cost-effectiveness of a multi-component

intervention programme targeting the school and family environment through primary

schools, in preventing obesity in 6–7 year old children, compared to usual practice.

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Confidential: For Review OnlyMethods

This cluster randomised controlled trial is set in 54 primary schools within the West

Midlands, UK, including a multi-ethnic, socioeconomically diverse population of children

aged 6–7 years.

The 12-month intervention consists of healthy diet and physical activity promotion. These

include: activities to increase time spent doing physical activity within the school day,

participation in the „Villa Vitality‟ programme (a programme that is delivered by an iconic

sporting institution (Aston Villa Football Club), which provides interactive learning

opportunities for physical activity and healthy eating), healthy cooking skills workshops in

school time for parents and children, and provision of information to families signposting

local leisure opportunities. The primary (clinical) outcome is the difference in body mass

index (BMI) z-scores between arms at 3 and 18 months post-intervention completion. Cost

per Quality Adjusted Life Year (QALY) will also be assessed. The sample size estimate

(1000 children split across 50 schools at follow-up) is based on 90% power to detect

differences in BMI z-score of 0.25 (estimated ICC ≤ 0.04), assuming a correlation between

baseline and follow-up BMI z-score of 0.9. Treatment effects will be examined using mixed

model ANCOVA. Primary analysis will adjust for baseline BMI z-score, and secondary

analysis will adjust for pre-specified baseline school and child level covariates.

Discussion

The West Midlands ActiVe lifestyle and healthy Eating in School children (WAVES) study

is the first trial that will examine the cost-effectiveness and long term outcomes of a

childhood obesity prevention programme in a multi-ethnic population, with a sufficient

sample size to detect clinically important differences in adiposity. The intervention was

developed using the Medical Research Council framework for complex interventions, and

outcomes are measured objectively, together with a comprehensive process evaluation.

Trial registration

Current Controlled Trials ISRCTN97000586 (registered May 2010).

Keywords

Cluster randomised controlled trial, Complex intervention, Childhood obesity prevention,

Physical activity, Healthy eating, Cost-effectiveness

Background

Childhood overweight and obesity is an ever increasing public health concern [1] which has

serious health consequences in both child [2] and adult life [3]. Children as young as 7 years

old, who are obese, are at higher risk of premature mortality in adulthood, compared to their

normal weight counterparts [4] and from the age of 11 years, there is tracking of behaviours

[5], such that over 50% of obese children become obese adults [6]. In England childhood

obesity rates have increased over the last 20 years. A doubling of prevalence of obesity can

be observed between the ages of 4 and 11 years (the primary school years) [7]. This is the

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Confidential: For Review Onlytime period of adiposity rebound, which occurs following a nadir in Body Mass Index (BMI)

around the age of 5–6 years [8]. Thus the primary school years are a key time period for

targeting interventions for the prevention of childhood obesity. In terms of settings, schools

are an environment in which the majority of children spend a sustained period of time. They

provide an infrastructure through which children and their parents can be identified and

receive, both within and outside the curriculum, opportunities to learn about, practice and

reinforce healthy lifestyle behaviours.

Several systematic reviews [9-11] have summarised the outcomes of previous childhood

obesity prevention studies, undertaken in a variety of settings including school, community

and family. The most up-to-date Cochrane review of trials, published in 2011, showed that

school based interventions, particularly those targeting 6–12 year olds, are effective in

reducing adiposity (mean effect size −0.15 for BMI z-score). However, there was much

heterogeneity in intervention components and design and generally small sample sizes.

Furthermore previous trials were poor at reporting process and implementation measures,

rarely considered equity of effects in relation to sex, ethnicity or other subgroups, tended not

to report longer term outcomes and seldom reported on adverse effects or costs.

Development of a childhood obesity prevention programme

The Birmingham healthy Eating and Active lifestyle for CHildren Study (BEACHeS) was

funded by the UK National Prevention Research Initiative and took place from 2006 to 2009.

The study used the early phases of the UK Medical Council Research framework for complex

intervention development and evaluation [12] to develop a childhood obesity prevention

programme aimed at children aged 6–8 years, and tested its feasibility and acceptability in an

exploratory trial. A number of different methodologies were employed and iteratively

combined in the theoretical and modelling phases of intervention development [13]. These

included a review of childhood obesity prevention evidence, focus groups with key

stakeholders to explore their views of the causes of childhood obesity [14] and their

perceptions of preventive approaches, consultation with a group of professionals, and a

review of existing local resources and national policy. The Analysis Grid for Environments

Linked to Obesity (ANGELO framework) [15] was applied during the development process

to ensure the intervention addressed all relevant environmental dimensions. The initial

programme consisted of two broad strands: increasing children‟s physical activity levels

through school, and family healthy behaviour skills (food preparation and physical activity)

through activity based learning. The programme was tested and further refined through a

feasibility study involving eight primary schools in Birmingham, UK [16], which provided

justification for a more definitive evaluation of the intervention.

In this paper we describe the study protocol for the definitive evaluation (a cluster

randomised controlled trial); the West Midlands ActiVe lifestyle and healthy Eating in

School children (WAVES) study, funded by the UK National Institute for Health Research

(NIHR) Health Technology Assessment programme.

Trial aims and objectives

The main aim is to assess the clinical and cost-effectiveness of the 12-month childhood

obesity prevention intervention programme, developed and refined in the BEACHeS study,

using usual practice in primary schools as the comparator. Intervention effects will be

examined at 3 and 18 months post-intervention completion. Cost-effectiveness of the

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Confidential: For Review Onlyintervention will be assessed from a societal perspective. In addition, differences in

intermediate and final outcomes will be explored by sex, ethnicity, socioeconomic status and

weight status. We will also use a variety of methods to describe the implementation of, and

adherence to, intervention components [17].

Trial design and overview

The WAVES study is a cluster-randomised controlled trial. Primary schools (n = 54) are

recruited from a multi-ethnic population within the West Midlands, UK. Randomization is at

the level of the cluster (school). Data are collected at both the cluster (school) and within

cluster (individual pupils and their parents) level. To test the effect of the intervention, a

range of anthropometric and psychological data are collected (described in detail later) on

children within participating schools. Baseline measures are undertaken when the

participating children are in Year 1 (April to July; aged 5 to 6 years). Schools are then

randomly allocated to either the usual practice or intervention arm. Schools in the

intervention arm are asked to implement a 12 month, multifaceted intervention programme

(details below) when children are in Year 2 (aged 6 to 7 years). The programme includes

physical activity and dietary components, targeting the school and family environments and

aims to help children maintain a healthy weight, thereby preventing overweight/obesity. Due

to practical considerations, half the schools (Group 1) are recruited to commence the study in

the 2011/12 school year and the remainder (Group 2) in the 2012/13 school year. First

follow-up measures are undertaken immediately after the intervention year (September to

December, when the children are in Year 3; aged 7 to 8 years) and second follow-up

measures are undertaken 18 months post intervention (January to March, when the children

are in Year 4; aged 8 to 9 years). Group 1 schools receive a third set of follow-up measures

27 months post intervention completion (September to December when in Year 5; aged 9 to

10 years). A summary of the study design and timelines is shown in Figure 1.

Figure 1 Study design and the flow of study participants through the WAVES study.

NHS Research Ethics approval for the trial was obtained from the Black Country Research

Ethics Committee (NHS REC no.10/H1202/69). The trial was registered in May 2010

(ISRCTN97000586).

Methods

Study setting and participant eligibility

All state primary schools in the West Midlands (UK) which included school years 1 to 5

(children aged 5 to 10 years) and that were within a 35 mile radius of the University of

Birmingham were eligible for inclusion (n = 980). To ensure sufficient representation in the

sample to enable sub-group analysis by minority ethnic group, school populations were

stratified by ethnic mix including White, South Asian (comprising Indian, Bangladeshi and

Pakistani) and Black (including African and Caribbean), with the remainder being classified

as “Other” ethnicity. School populations were dichotomised as being in the top 80th

percentile in terms of South Asian or Black pupil representation, or not. The sampling

strategy used a weighted random sample so that schools with a higher minority ethnic

population (in top 80th percentile for South Asian or Black) had an increased chance of being

sampled with a ratio of 3:1. Given the relatively large number of clusters (>50) the sampling

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Confidential: For Review Onlystrategy was also balanced to take account of three other important factors to ensure a range

of characteristics are represented. These were: proportion of children eligible for free school

meals (FSM) as an indicator of socio-economic make-up of the pupils, school size and

urban/rural location of the school. Using this method, 200 schools were selected and ordered

using a random number generator. Of these, 7 were excluded as they did not fit the eligibility

criteria. The remaining schools were sequentially invited to participate, and 148 were

approached until the required sample size (54 schools) was achieved. Of the 148 schools

approached, 4 did not respond and 90 declined to participate.

Exclusion criteria

Schools with fewer than 17 pupils in the relevant year group (minimum cluster size), or those

that were in special measures (status applied by the Office for Standards in Education when it

considers that a school fails to supply an acceptable level of education and appears to lack the

leadership capacity necessary to secure improvements) were excluded.

School recruitment process

Schools were approached by letter, followed by a phone call and a visit to interested schools.

All participating schools (control and intervention) receive a financial reimbursement (£190)

following each period of pupil measurement to compensate for staff time spent on the study.

Regular newsletters are sent to participating schools to maintain engagement.

Recruitment of study participants

All Year 1 pupils (aged 5 to 6 years) in participating schools were eligible to take part. An

invitation letter, information leaflet and consent form were distributed through schools to

parents/carers of eligible pupils.

Trial intervention

The WAVES study intervention programme has four components (outlined below) delivered

over 12 months. There is also a termly family newsletter to reinforce the messages delivered

through the various components. The schools are used as the platform for disseminating

information, targeting intervention children and their families, and as the venue for some of

the intervention components. Each component has fixed parameters as well as elements that

allow tailoring to specific populations, enabling schools to adapt the delivery by taking

account of local circumstances. Relevant school staff members are provided with a manual

and a short training session on delivering the intervention. Follow-up support for intervention

delivery is provided by research staff in the first few weeks. No further support is provided

for the remaining intervention period.

Schools in the intervention arm receive reimbursement (£380) to cover costs incurred through

their involvement with the intervention (such as staff cover for teacher training).

Component 1: Structured physical activity opportunities during the school day

The overall aim of this component is to increase physical activity opportunities within the

school day, with a target for children to achieve an additional 30 minutes of moderate to

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Confidential: For Review Onlyvigorous physical activity (MVPA) per day. Teachers can select two from a choice of four

activity programmes which are available in the UK market; „Activate‟ [18], „Positive Play‟

[19], „Take 10‟ [20] or „Wake Up Shake Up‟ [21]. These programmes were selected as they

could be tailored to each school setting and incorporate a range of classroom and playground

based routines to help children be active in a school environment with minimal disruption to

the regular school day.

Component 2: Cooking skills workshops for children and parents

The aim of this component is to increase healthy eating knowledge and improve food

preparation skills of parents and children. A series of three workshops, designed by research

nutritionists for children and their parents or carers, is delivered by school staff. Each

workshop was piloted (with 6 to 8 children aged 6–7 years and their parents) and the content

and format modified as necessary prior to completion. Relevant school staff members are

invited to attend interactive training on the content and delivery of the workshops, where they

are provided with all relevant materials (including lesson plans and presentation slides) and

participate in a practical session. The workshops, which are intended to be delivered once per

term through the school year, focus on „breakfast‟, „lunch and snacks‟ and „evening meal‟.

Key messages are consistently included across all sessions to increase fruit, vegetable and

fibre intakes, and decrease fat and sugar intakes. Each workshop is preceded by three 10

minute lessons for the children in class time to prepare them for the topics to be covered.

During the workshop an interactive educational session is followed by practical food

preparation, where children work with their parents to prepare healthy food that they can eat

together. Written information emphasising key messages is given to parents and carers to take

home after the workshops.

Component 3: Signposting

The aim of this component is to increase participation in physical activity out of school hours.

Children are given two information sheets to take home, signposting opportunities and

facilities for them and their family to be physically active. Following baseline measures,

children in intervention schools are given a brightly coloured information sheet which

highlights the UK government recommendation of at least 60 minutes of moderate to

vigorous physical activity a day [22], and uses motivational statements (such as encouraging

goal setting) as well as information and ideas for how children and their families could be

active over the summer holidays. The focus is on everyday opportunities such as walking and

physical activities that could be done in the home. At the beginning of the following term,

they are given more specific information, which again highlights the 60 minutes of activity

message, and gives details of clubs, leisure centres, parks and other opportunities suitable for

families with young children to undertake physical activity within close proximity of their

school.

Component 4: Villa Vitality

The aim of this component is to promote healthy lifestyle messages through an iconic sports

institution and its staff. Villa Vitality (VV) is a programme run at Aston Villa Football Club

(AVFC; a premier league English football club), focusing on promoting healthy eating and

physical activity through interactive sessions delivered at AVFC. The programme, originally

designed for older children, has been adapted for the WAVES study by collaboration between

VV staff and the research team. All the messages delivered as part of the programme are

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Confidential: For Review Onlyconsistent with the other components of the WAVES study intervention. The revised

programme was piloted with a sample of Year 2 children (n = 60) before implementation in

the study intervention arm.

The VV programme involves two day trips to AVFC, six weeks apart. The children

participate in a range of activities during these days. These include: physical activity games

and ball skills, two nutrition education sessions, dance mats, preparing a meal in the VV

kitchen, a tour of the stadium and a session in the VV radio studio. During the intervening 6

weeks, the children are encouraged to participate in weekly health challenges (achieve 60

minutes of activity every day, swap a snack, drink more water, eat a healthy breakfast every

day, eat 5 portions of fruit and veg every day and cook a healthy family meal), and undertake

a class project (to produce a song, story or poem about healthy living for recording during

their session in the VV radio studio). The children also receive a 60 minute physical activity

session run at school by an Aston Villa Football Academy coach. During this visit the coach

also reviews progress in relation to both the class project and the weekly challenges.

Comparator

Schools in the usual practice (control) arm are sent citizenship education resources [23] to use

as they wish (the topics of healthy eating and physical activity are intentionally avoided). No

other active intervention is offered. These schools continue with any ongoing health related

activities.

Method of random allocation and blinding

A blocked balancing algorithm is used to randomise schools to either the intervention or

control arm [24,25]. This algorithm randomly selects one of a number of allocation designs

which minimise the imbalance between covariate means. The covariates included are

percentage of pupils within the school eligible for free school meals; percentage of South

Asian pupils within the school; percentage of Black pupils within the school; percentage of

White pupils within the school; and number of pupils within the school. Randomisation is

undertaken after baseline measurements, and participating schools are then informed of

allocation.

Outcome measures

For clinical effectiveness, the primary outcome is the difference in body mass index (BMI) z-

scores (using the UK 1990 BMI reference curves for children [26]) between arms at 3- and

18-month follow-up post-intervention completion. Secondary outcomes include: i)

anthropometric measures: percentage overweight and obese (defined as a BMI greater than

the 85th percentile on the UK 1990 reference charts for BMI centiles for boys and girls),

skinfold thickness at 5 sites (biceps, triceps, thigh, suprailiac and subscapular), waist

circumference and percentage body fat; ii) blood pressure; iii) dietary energy (kJ per kg body

weight per day), fat, sugar, fibre (g/day), and fruit and vegetable intake (g/day and portions);

iv) physical activity energy expenditure (kJ per kg body weight per day), and time spent

doing sedentary, light, moderate and vigorous intensity activity (min/day), v) psychosocial

outcomes to assess the wider effects of the intervention, including benefits and potential

harms: health related quality of life and body dissatisfaction, and vi) longer term clinical

effectiveness at 27 months post intervention in Group 1 schools.

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Confidential: For Review OnlyFor cost-effectiveness analysis, the primary outcome is cost per Quality-Adjusted Life Year

(QALY). Other analyses will include cost per effectiveness outcomes such as change in BMI

z-score and change in proportion of overweight/obese. A longer term model-based evaluation

will predict cost-per-QALY outcomes over a lifetime by linking a change in weight status in

childhood to future health outcomes in adulthood.

Data collection methods

Pupils‟ date of birth, sex, ethnicity and postcode (to derive a proxy measure for deprivation)

data are obtained from parent questionnaire, or if not available, from school records.

Assessments are undertaken in school by trained research staff, using standardised procedures

(available on request) and validated instruments at baseline and follow-up time points. In

addition, parents of participating children are asked to complete questionnaires at each time

point. These cover questions on child and parent demographics, dietary, sedentary, physical

and sleep activity habits, home food environment, perceived neighbourhood environment and

proximity to food and leisure facilities, family cooking habits and participation in leisure

activities.

Anthropometric measures

All measurements are undertaken barefoot and in light clothing. Standing height is measured

at least twice (with a third measure if difference is >0.4 cm) with a Leicester Height Measure.

Weight and body fat percentage are measured with a Tanita bioimpedance monitor (Tanita

SC-331S; Tanita Corporation., Tokyo, Japan). Waist, arm and thigh circumference are

measured at least twice (with a third measure if difference is >0.4 cm, 0.2 cm or 0.2 cm,

respectively) using a non-stretch tape-measure. Skinfold thickness at five sites (biceps,

triceps, subscapular, suprailiac and thigh) are measured at least twice (with a third measure if

difference is >0.4 cm) on the non-dominant side, using a Holtain Tanner / Whitehouse

Skinfold Caliper (Holtain Ltd., UK).

Dietary assessment is undertaken using a validated [27] simple tick list, the Child and Diet

Evaluation Tool (CADET), which is completed by researchers (in school) and parents (out of

school) over a 24 hour period. The tool enables estimation of total energy, macro and micro-

nutrient intake.

Physical activity energy expenditure and its sub-dimensions (i.e. time spent sedentary and in

light, moderate and vigorous intensity activity) is assessed objectively over a 5 day period

(including a weekend) using a monitor that combines heart rate and accelerometry (Actiheart,

Cambridge Neurotechnology Ltd, Papworth, UK), which has excellent technical validity and

reliability [28] and has been validated in young children [29].

Blood pressure

Blood pressure is measured using clinically validated, automated, oscillometric BP monitors

(BpTRU BPM-100, British Columbia, Canada) [30], with the appropriate cuff-size used for

each child. After 3 minutes seated-rest, two readings are taken with a 3 minute rest-interval

between each. A third measurement is taken if an error reading occurs, or if one of the values

is outside the normal range.

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Confidential: For Review OnlyOther measures

Psychosocial measure are collected through researcher administered questionnaires to

children. Quality of life is measured using the Pediatric Quality of Life Inventory (PedsQL)

[31]; social acceptance is measured using the relevant domain from the Kidscreen-52 health

questionnaire for children and young people [32] and body image is assessed using the

Children‟s Body Image Scale [33]. The pediatric preference-based utility instrument, Child

Health Utility 9D [34] is also completed to inform the economic evaluation.

School level data

Data on participating schools are collected through a questionnaire administered to head

teachers or a nominated representative. Information requested includes details on school food

and physical activity policies and any relevant initiatives or programmes delivered through

school.

Process evaluation

Implementation fidelity is assessed throughout the intervention year using a range of methods

including direct observation, logbooks, parent and school staff questionnaires, research staff

experiences and qualitative evaluation. The methods are described in detail elsewhere [17].

Justification of sample size

Sample size calculation is based on the primary outcome (BMI z-score). Further calculations

were also performed to estimate power for the secondary outcome of percentage of children

overweight or obese. Planned analysis of the WAVES study will compare outcomes for

control and intervention schools at follow-up times, adjusting for baseline measurements.

Therefore power calculations undertaken were based on repeated measures methods using

estimates of correlation between before and after measurements. A modified version of the

design effect [35] was used to estimate sample size and accommodate varying cluster sizes

(using the estimated: mean cluster size (n = 25; SD = 23). For the primary outcome of BMI z-

score, a follow-up sample size of 1000 children split across 50 schools gives the study greater

than 90% power to detect a difference of 0.25 BMI z-score between intervention and

comparator groups (equivalent to approximately 0.5 kg body weight for a 7-year old child)

under all likely estimates of the intraclass correlation coefficient (ICC = 0 to 0.04, estimated

correlation between before and after measures = 0.9 and estimated dropout rate = 20%). A

change of 0.25 in BMI z-score has been shown to be associated with clinically detectable

benefits in obese adolescents [36] and longitudinal studies demonstrate a linear relationship

between BMI z-score in children as young as 7 and heart disease events in adulthood [4].

Under more conservative estimates for the ICC, this sample size would provide more than

80% power to detect a 0.125 difference in BMI z-score. A BMI z-score difference as low as

0.125 is the primary outcome of choice for other childhood obesity prevention trials [37].

Allowing for school drop-out (~8%), 54 schools were therefore invited to take part.

For the secondary outcome of percentage overweight/obese, this sample size (with an

estimated correlation of before and after measures of 0.7 and an ICC of between 0 and 0.02)

provides greater than 80% power to detect a difference in the change of proportion of

children who are overweight/obese from baseline to follow-up in control compared to

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Confidential: For Review Onlyintervention schools of about 7% (exact value depends on baseline values). All power

calculations were carried out in STATA using the clustersampsi function [38].

Data quality and management

All study data are stored in a password-protected customised database, hosted by the

University of Birmingham. Paper-based information is held in locked filing cabinets in the

study office. For all data entry, a minimum 10% sample is checked to monitor error rates.

Potential errors are identified and checked using a range of techniques. These include clinical

and data-driven range checks, and cross validation between variables where a correlation

would be expected and when the same information is obtained from different sources.

Planned statistical analysis

Trial analyses will be undertaken after the second follow-up measures are completed and

there will be no interim analyses.

The baseline pupil (including sex, ethnicity, deprivation [based on IMD scores derived from

home postcode] anthropometric measures, dietary intake, physical activity levels,

psychological variables) and school level characteristics (school size, ethnic mix of pupils

and % eligible for FSM) will be summarised by control and intervention arms, using numbers

and proportions, means and standard deviations or medians and inter-quartile ranges.

Analyses of outcomes will be by intention to treat. As randomisation will be at the school

(cluster) level, appropriate statistical methods to account for the clustering within schools

(detailed below) will be used in the analysis. Analysis of outcomes will be for both 3- and 18-

month follow-up stages.

We will use a mixed model ANCOVA with follow-up outcome values as the dependent

variable and baseline values and treatment arm as the independent variables, to investigate

effectiveness. These will be fitted using mixed models in STATA to allow for clustering. We

will allow for clustering at the school level and explore the possibility of allowing for an

additional level of clustering at the class level.

The primary analysis will be adjusted for baseline values for all outcomes. Secondary

analysis will additionally adjust for pre-specified baseline school and child level covariates.

These will include school level factors which were used in the randomisation (school size, %

pupils eligible for free school meals, ethnic mix of pupils) and pupil level factors (sex,

baseline BMI z-score, ethnicity, deprivation from home postcode, baseline total energy intake

and baseline total physical activity). We will not adjust for age as all children will be of a

very similar age. We will adjust at the school and pupil level for both ethnicity and

deprivation as the school population is expected to differ from the consented study

population.

Outcomes are either binary (e.g. non-overweight vs. overweight), or continuous (e.g. BMI z-

score or energy expenditure), and therefore either log or linear link functions will be used,

with transformations where appropriate to accommodate any non-normality. All model

assumptions will be checked. We will report both relative and absolute treatment effects.

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Confidential: For Review OnlyThe primary analysis will be a complete case analysis. However, missing data will be

reported and associations between outcomes explored. Depending on the nature of these

associations and the extent of the missing data, sensitivity analysis will be undertaken using

multiple-imputation techniques.

The primary outcome and primary sub-group comparisons at both time points will be

considered significant at the 5% level (and so 95% CIs reported); whereas other secondary

outcomes will be deemed significant at the 1% level (and so 99% CIs reported). This

difference in levels of significance, gives more weight to the primary outcomes.

Planned subgroup analyses

An examination of whether any difference in outcomes between control and intervention

arms varies by sex, weight status at baseline, ethnic mix of the school and socio-economic

factors will be undertaken. Within the intervention arm, we will also look at differences in

outcome by fidelity of implementation (broadly classified as low, medium or high).

The significance of subgroup effects will be assessed by tests of interactions of covariates and

the treatment effect. The study will have low power to detect all but the largest differences in

subgroups.

Economic evaluation

The economic evaluation will estimate the incremental cost and incremental benefit of the

WAVES study intervention compared to usual current practice, from a NHS/educational

service perspective. Additional wider perspectives, such as inclusion of family members, will

be explored as part of a sensitivity analysis. A within-trial analysis will estimate the cost-

effectiveness at 18 months assuming that the intervention is in a „steady state‟ and thus will

not include set up or implementation costs. A longer term analysis will estimate the cost

effectiveness using a decision-analytic model.

The within-trial analysis will adopt a micro-costing approach to estimate the costs of each

intervention component. Trial report forms and school logbooks will collect resource use

information for staff time, materials, transport, and equipment, combined with unit cost data

to estimate the incremental intervention mean cost per class, and per child. Sensitivity

analysis will explore intervention fidelity, and the inclusion/exclusion of categories of cost

e.g. family members, set up, implementation. Quality of life will be measured using the

Child-Health Utility 9D instrument and expressed as QALYs. Cost-effectiveness will be

measured using both the effectiveness outcomes (BMI z-score, proportion overweight/obese)

and QALY outcomes.

The long-term cost effectiveness analysis will use a decision-analytic model to predict the

cost-savings and outcomes from preventing overweight/obesity in childhood. Model

parameters will be informed by a literature review and will map outcomes from childhood to

adulthood. Extensive sensitivity analysis will be carried out, to test for the robustness of the

conclusions to assumptions made in the modelling, and to sampling variation in the data used

in the construction of the model. Costs and benefits will be discounted at the standard rate

(3.5%).

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Confidential: For Review OnlyTrial status

The trial started recruitment of schools in January 2011, and of pupils from March 2011.

Intervention delivery was completed in July 2013. Final follow-up measurements will be

completed in April 2015. Data analysis will commence following data cleaning (after June

2015). The expected report date is November 2015.

Discussion

To our knowledge, the WAVES study is the first trial of a childhood obesity prevention

intervention that: has been developed using the MRC framework for complex interventions,

tests both the clinical and cost-effectiveness of a school-based intervention and will have

sufficient length of follow-up to examine longer term effects. The trial setting includes a

diverse socioeconomic and multi-ethnic population to allow exploration of sub-group effects.

There is also consideration of a wide range of outcomes, including psychosocial effects to

monitor potential harm.

The trial will address some of the limitations identified in previous research [9], particularly

including a sample size large enough to detect clinically significant differences in adiposity,

use of an objective measure of physical activity, inclusion of cost effectiveness evaluation, a

comprehensive process evaluation and assessment of longer term outcomes (all schools at 18

months and half the schools at 27 months post intervention completion).

Given the pragmatic and complex nature of the trial, it will not be possible to assess

intervention efficacy directly or to disentangle the relative contribution of different

intervention components to any observed outcomes. On the other hand, assessment of

effectiveness in real settings facilitates future intervention roll-out and dissemination, should

the intervention prove to be clinically cost-effective. Thus, the study has the potential to

influence health and education policy in the UK and further afield.

The comprehensive process evaluation and detailed assessment of implementation alongside

the trial will allow us to contextualise and explain the findings of the trial and inform future

implementation. It will also allow us to perform analyses to explore the relationship between

intervention implementation and outcomes, which has not been undertaken in previous

childhood obesity prevention trials.

In addition to the findings of the trial, the study will also provide a large dataset on the weight

status and other health indicators of a sub sample of multi-ethnic children in the West

Midlands, which can be used to address other relevant research questions.

Abbreviations

ANGELO, Analysis Grid for Environments Linked to Obesity; BEACHeS, Birmingham

healthy Eating and Active lifestyle for CHildren Study; BMI, Body Mass Index; CADET,

Child and Diet Evaluation Tool; FSM, Free school meals; ICC, Intraclass correlation

coefficient; MRC, Medical Research Council; MVPA, moderate to vigorous physical

activity; NIHR, National Institute for Health Research; PedsQL, Pediatric Quality of Life

Inventory; WAVES, West Midlands ActiVe lifestyles and healthy Eating in School children

study; VV, Villa Vitality.

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Confidential: For Review OnlyCompeting interests

The authors declare that they have no competing interests.

Authors’ contributions

All WAVES study Trial Co-investigators contributed to the development of the design for the

WAVES study trial and had contributed to the intervention development as part of the

BEACHeS study. PA, MP and KKC planned the overall design. EF designed the economic

evaluation methods and analysis plan. JJD and KH contributed to sampling, sample size

estimation and the statistical analysis plan. UE advised on physical activity measurements

and related methods. JEC advised on dietary assessment and related methods. JLD advised on

some of the psychosocial assessment methods. TB, PG and RB advised on clinical

measurement processes. RB and PG advised on aspects related to ethnicity. AD advised on

the physical activity intervention component. SP advised on school recruitment and

approaches to keeping schools engaged. EM advised on the dietary intervention components.

JP advised on process evaluation, and TG designed the detailed methods for this. ERL co-

ordinated the trial development and implementation, and co-wrote the first draft of the

protocol with TG, with substantial contribution from PA and MJP. All authors contributed to

critical revisions of the paper. The final manuscript was read and approved by all authors.

Acknowledgements

Trial Monitoring

The Trial Steering Committee meets annually to advise the research team. Chair/ statistician:

Dr Kelvin Jordan, Keele University Subject expert: Professor Peter Whincup, St George‟s,

University of London Health economist: Dr Louise Longworth, Brunel University Public

representative: Mr John Bennett, PHSE advisor Investigators: Prof Peymane Adab, Dr

Miranda Pallan, University of Birmingham.

Data monitoring committee

Due to the timelines of recruitment and outcome assessments, there is no opportunity for

interim analyses, and hence there is no role for a separate DMC for this trial. The TSC

undertakes assessment of data quality and completion.

Sponsor and Indemnity

The University of Birmingham holds the relevant insurance policy for this study and acts as

the main sponsor.

Funding

This project was funded by the National Institute for Health Research (NIHR) Health

Technology Assessment Programme (Project Reference Number 06/85/11). UE is funded by

the Medical Research Council (MC_UU_12015/4).

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Confidential: For Review OnlyDepartment of Health Disclaimer

The views and opinions expressed therein are those of the authors and do not necessarily

reflect those of the HTA, NIHR, NHS or the Department of Health.

The funders have played no role in the design, collection, analysis, and interpretation of data,

nor in the writing of the manuscript and in the decision to submit the manuscript for

publication.

WAVES study trial investigators

University of Birmingham: Peymane Adab (Professor of Public Health and Chief

Investigator), Tim Barrett (Professor of Paediatrics), KK Cheng (Professor of Epidemiology)

Amanda Daley [1] (NIHR Senior Research Fellow), Jonathan J Deeks (Professor of

Biostatistics), Joan L Duda (Professor of Sport and Exercise Psychology), Emma Frew [1]

(Senior Lecturer in Health Economics), Paramjit Gill (Clinical Reader in Primary Care

Research), Karla Hemming (Senior Lecturer in Medical Statistics), Miranda J Pallan (Clinical

Research Fellow), Jayne Parry [1] (Professor of Policy and Public Health); University of

Cambridge, Cambridge MRC Epidemiology Unit / Norwegian School of Sport Sciences: Ulf

Ekelund (Professor of Physical Activity Epidemiology and Public Health/Senior Investigator

Scientist); University of Leeds: Janet E Cade (Professor of Nutritional Epidemiology and

Public Health); The University of Edinburgh: Raj Bhopal (Bruce and John Usher Chair in

Public Health); Birmingham Community Healthcare NHS Trust: Eleanor McGee (Public

Health Nutrition Lead); Birmingham Services for Education: Sandra Passmore ( Education

Advisor).

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bmj · confidential: for review only 2 abstract objectives: to assess the effectiveness of a school...

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