Effectiveness of an Implementation Optimisation Intervention Aimed at Increasing Parent Engagement in HENRY, a Childhood Obesity Prevention Programme: a Cluster Randomised Controlled Trial
Phase: PHASE3
Conditions: Childhood Obesity
Sponsor: University of Leeds

STUDY PROTOCOL
Open Access
Effectiveness of an implementation
optimisation intervention aimed at
increasing parent engagement in HENRY, a
childhood obesity prevention programme -
the Optimising Family Engagement in
HENRY (OFTEN) trial: study protocol for a
randomised controlled trial
Maria Bryant1*
, Wendy Burton1, Bonnie Cundill1, Amanda J. Farrin1, Jane Nixon1, June Stevens2,3, Kim Roberts4,
Robbie Foy5, Harry Rutter6, Suzanne Hartley1, Sandy Tubeuf7, Michelle Collinson1 and Julia Brown1
Abstract
Background: Family-based interventions to prevent childhood obesity depend upon parents’ taking action to
improve diet and other lifestyle behaviours in their families. Programmes that attract and retain high numbers of
parents provide an enhanced opportunity to improve public health and are also likely to be more cost-effective
than those that do not. We have developed a theory-informed optimisation intervention to promote parent
engagement within an existing childhood obesity prevention group programme, HENRY (Health Exercise Nutrition
for the Really Young). Here, we describe a proposal to evaluate the effectiveness of this optimisation intervention in
regard to the engagement of parents and cost-effectiveness.
Methods/design: The Optimising Family Engagement in HENRY (OFTEN) trial is a cluster randomised controlled
trial being conducted across 24 local authorities (approximately 144 children’s centres) which currently deliver
HENRY programmes. The primary outcome will be parental enrolment and attendance at the HENRY programme,
assessed using routinely collected process data. Cost-effectiveness will be presented in terms of primary outcomes
using acceptability curves and through eliciting the willingness to pay for the optimisation from HENRY commissioners.
Secondary outcomes include the longitudinal impact of the optimisation, parent-reported infant intake of fruits and
vegetables (as a proxy to compliance) and other parent-reported family habits and lifestyle.
(Continued on next page)
* Correspondence: m.j.bryant@leeds.ac.uk
1Leeds Institute of Clinical Trials Research, University of Leeds, Leeds LS29JT,
UK
Full list of author information is available at the end of the article
© The Author(s). 2016 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0
International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and
reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to
the Creative Commons license, and indicate if changes were made. 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.
Bryant et al. Trials  (2017) 18:40 
DOI 10.1186/s13063-016-1732-3

(Continued from previous page)
Discussion: This innovative trial will provide evidence on the implementation of a theory-informed optimisation
intervention to promote parent engagement in HENRY, a community-based childhood obesity prevention programme.
The findings will be generalisable to other interventions delivered to parents in other community-based environments.
This research meets the expressed needs of commissioners, children’s centres and parents to optimise the potential
impact that HENRY has on obesity prevention. A subsequent cluster randomised controlled pilot trial is planned to
determine the practicality of undertaking a definitive trial to robustly evaluate the effectiveness and cost-effectiveness
of the optimised intervention on childhood obesity prevention.
Trial registration: ClinicalTrials.gov identifier: NCT02675699. Registered on 4 February 2016.
Keywords: Engagement, Trial, Implementation, Childhood obesity, Parent, Recruitment
Background
Although the most recent data suggest a levelling off of
the prevalence of childhood obesity in the United
Kingdom, levels remain high and there are clear inequal-
ities, with rates continuing to rise in more deprived and
ethnic minority groups [1]. Childhood obesity impacts
physiological and psychological health, which tracks into
adulthood [2, 3], increasing the risk of morbidity and
mortality [4, 5]. It imposes significant costs on the U.K.
economy, with an expected sevenfold increase in related
NHS costs by 2020 and a forecasted £2 billion annual
spend by 2030 [6]. Tackling obesity is a national public
health priority in terms of both treatment and preven-
tion. Establishing healthy behaviours in early childhood
is critical for optimum growth and development [7]. Fur-
ther, poor eating patterns developed early can persist
and are associated with chronic diseases in adulthood
(e.g., cardiovascular disease, type 2 diabetes mellitus [8]).
Once established, obesity is difficult to reverse [9],
strengthening the case for primary prevention [10, 11].
To reverse trends in obesity, there is a clear need to en-
gage parents in shaping healthy weight-related behav-
iours in their children.
Design, implementation and evaluation of interven-
tions to prevent or treat obesity may be expensive and
time-consuming, and researchers often report a lack of
effectiveness [12–15]. Within the literature on childhood
obesity, low parent enrolment and attendance at group-
delivered programmes, along with a lack of reported be-
haviour change, are commonly described to have had a
substantial impact on group dynamics, effectiveness and
cost-effectiveness [16–18].
There is a need for pragmatic, ‘real-world’ evaluations
of interventions to understand the generalisability of the
interventions across everyday practice [19, 20]. Further,
in order for interventions to be accurately implemented
and interpreted, the underpinning behaviour change
techniques need to be clearly defined [21]. Implementa-
tion optimisation strategies can then be adopted to tar-
get
a
specific
intervention
component
[22].
It
is
imperative that parent engagement be improved across
all parenting interventions delivered in community set-
tings to optimise their impact and so that the degree to
which they are effective can be assessed with confidence.
In contrast to conventional pathways, in which imple-
mentation research is conducted following trials for clin-
ical effectiveness [23], it is argued that there is a need
for comprehensive early-phase (evidentiary) evaluation
and enhancement of complex interventions such as
those designed to prevent childhood obesity [24], prior
to the conduct of large randomised controlled trials
(RCTs). This novel approach ensures that factors which
limit trial outcomes, such as low adherence, are mini-
mised prior to dedicating the resources required to con-
duct a large trial which may identify no evidence of
effectiveness, perhaps as a result of poor compliance.
The present trial involves the evaluation of an imple-
mentation enhancement ‘optimisation intervention’ of
an
existing
preschool
obesity
prevention
group
programme, HENRY (Health Exercise Nutrition for the
Really Young), to promote parent enrolment and attend-
ance prior to establishing its clinical effectiveness and
cost-effectiveness. HENRY is an 8-week group-delivered
programme provided to parents of preschool children. It
was developed in 2006 with joint funds from the Depart-
ment of Health and the Department for Education (then
called the Department of Children, Schools and Families)
and is currently commissioned and delivered across the
United Kingdom by 32 local authorities providing more
than 150 programmes each year. It is delivered in com-
munity settings, often in children’s centres by children’s
centre staff [25]. HENRY uses a responsive approach to
provide practical guidance and improve parenting skills
aimed at enhancing family lifestyle and children’s centre
environments. Preliminary data indicate that HENRY
may be effective at preventing childhood obesity and im-
proving family health [25], although there is not yet evi-
dence from an RCT.
Despite some indications of success of HENRY from
audit [25] and qualitative data [26–28], process evalu-
ation indicates implementation targets are often not
met. Lack of involvement by some parents may be a
Bryant et al. Trials  (2017) 18:40 
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threat to the viability of this programme and other, simi-
lar community-based interventions. The effectiveness of
interventions in real-world conditions may not match
the efficacy found in research studies [29]. This may be
particularly relevant to population-based prevention pro-
grammes, in which parents may be less likely to be moti-
vated to attend because their children show no clinical
symptoms [30, 31]. Thus, it is imperative to create tai-
lored methods to maximise parent participation and en-
hance successful implementation in childhood obesity
prevention programmes.
Failure to attend interventions is complicated by issues
of health inequalities; socio-demographic attributes; and,
in some cases, challenges related to safeguarding [30, 32,
33]. Literature on non-attendance in other areas (clinical
appointments) indicates that attendance is lower in cer-
tain populations and may be an indicator of vulnerability
[34]. This is pertinent to obesity because prevalence
rates continue to rise in children in lower socio-
economic or ethnic minority groups. In addition to the
anticipated public health benefits, the economic benefits
of implementation optimisation in programmes such as
HENRY are substantial, with one parenting intervention
calculating an extra £800 cost per child in programmes
that run with 8 parents compared with those running at
the intended capacity of 12 parents [35].
Unlike the development of other robust behaviour
change interventions, initiatives to improve parental at-
tendance at clinical appointments have been confined
largely to simple approaches such as text reminders [34,
36, 37]. To promote behaviour change, enhance the
transparency of interventions and guide their generalis-
ability, it is recognised that a systematic approach is
used during intervention development, which is under-
pinned by theories of behaviour change and guided by
an intervention-planning framework such as the Behav-
iour Change Wheel [24, 38]. Lessons can be learnt from
child mental health research, in which many interven-
tions have been developed and tested using robust
theory-based approaches which carefully consider parent
engagement [33]. Research in this field has explored per-
ceived barriers to participation with suggested strategies
to engage parents, including promotion of self-efficacy
and treatment motivation. Such strategies perceive par-
ents as the central agents of change and aim to modify
the pre-treatment experience [33, 39]. RCTs evaluating
parent engagement in mental health services [40] and
drug misuse [41] indicate that parental engagement can
be increased with a dedicated optimisation component,
although a further trial focused on cultural relevance for
child behaviour problems to optimise engagement [42]
did not find any increase.
To our knowledge, there are no theory-based, multi-
component optimisation interventions that have been
developed to optimise parent engagement in obesity pre-
vention programmes, and which have been evaluated
using an RCT design. To meet this need, we developed a
parent engagement optimisation intervention following
Medical Research Council (MRC) guidance for develop-
ment of complex interventions [38]. The Consolidated
Framework for Implementation Research was used to
understand contextual factors associated with the imple-
mentation of HENRY and their impact on parent en-
gagement [43]. The Behaviour Change Wheel [44]
provided guidance for the development of the interven-
tion, which features use of the ‘COM-B’ model (capabil-
ity, opportunity and motivation) to dissect behaviours
into their individual and interacting components and
consider which of these should be targeted in an inter-
vention to bring about the desired behaviour change. A
rapid ethnography was conducted in five children’s cen-
tres to understand the environmental, social, psycho-
social, political and economic factors associated with
parent engagement in HENRY. This study gathered data
from approximately 190 h of observations, 22 interviews
with children’s centre managers and staff, HENRY com-
missioners, and HENRY coordinators and facilitators. Six
focus groups were also conducted with parents who had
attended the programme. We convened an intervention
development team consisting of experts in intervention
development, obesity, applied health and behaviour
change, a local authority representative, a HENRY parent
champion, a parent who has attended the programme,
and a representative from the HENRY team. The inter-
vention team used evidence from the ethnography, from
the literature, and from their own experiences and ex-
pertise
to
develop
a
multi-component
optimisation
intervention which attempts to promote parent engage-
ment and positive behaviour change in families by sup-
porting local authorities, children’s centres, HENRY staff,
and parents using candidate implementation and deliv-
ery strategies (Career Development Fellowship CDF-
2014-07-052). Here we report the protocol of our cluster
randomised
controlled
trial
(cRCT)
(using
routine
process data) to evaluate the optimisation intervention
for its ability to engage parents in HENRY prior to con-
ducting a further evaluation of its clinical effectiveness.
Methods/design
Design
This study is a two-arm, multi-centre cRCT across 24
local authorities (local governments) (supporting ap-
proximately
144
children’s
centres)
in
the
United
Kingdom
to
determine
the
effectiveness
and
cost-
effectiveness of an optimisation intervention to promote
parent engagement in the HENRY programme com-
pared with standard HENRY practice (Fig. 1). Although
the children’s centres deliver the HENRY programme,
Bryant et al. Trials  (2017) 18:40 
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owing to the multi-component and interactive nature of
the optimisation intervention, local authorities will be
the units of randomisation (i.e., clusters) to prevent con-
tamination between the randomised groups. Outcomes
will be assessed through routinely collected data avail-
able for each HENRY programme at the parent and chil-
dren’s centre levels. Information on commissioners’
willingness to pay (within local authorities) related to
the optimisation intervention will be elicited. A process
evaluation will be conducted alongside the cRCT in ac-
cordance with the MRC guidance on evaluating process
in complex interventions [19].
Objectives
Primary objectives of the trial are to determine the
following:
1. The effect of the optimisation intervention applied
to HENRY compared with standard HENRY in
regard to increasing parent enrolment in HENRY
programmes or reducing parent attrition within
HENRY programmes
2. The willingness to pay of commissioners of the
HENRY programme per additional level of parent
engagement related to the optimisation intervention
(Costs will be presented as an incremental cost per
increase of parent engagement, so that commissioners
are able to identify the point at which additional costs
are acceptably offset by the benefits of engaging
effectively with parents.)
Secondary objectives of the study are to determine:
1. The effect of the optimisation intervention on
achieving combined parent enrolment, attrition and
compliance targets
2. The effect of the optimisation intervention on parent
compliance with HENRY programme content
3. The effect of the optimisation intervention on
parent-reported family habits and lifestyle
4. The potential longitudinal impact (sustainability) of
the optimisation intervention on enrolment and
attrition in centres that provide data from more
than one programme
Setting
The study will be conducted in local authorities with
children’s centres where staff are currently trained to de-
liver the HENRY programme. There are currently 32
local authorities (approximately 144 centres) in the
United Kingdom running the programme, all of which
provide process data to the central HENRY office for
monitoring/quality assurance (QA) purposes. These data
will be anonymised and transferred for analysis.
Inclusion criteria
Local authorities comprising the following:
 Local authorities that commission HENRY and
consent for their centres to be involved in the
research
 Commissioning HENRY programmes delivered by
trained staff who have been certified by HENRY
Children’s centres comprising the following:
Fig. 1 Trial design flow diagram. HENRY Health Exercise Nutrition for the Really Young, ITT Intention to treat
Bryant et al. Trials  (2017) 18:40 
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 Centres providing routinely collected data for the
most recent HENRY programme that they ran at
the point of randomisation
Exclusion criteria
Local authorities:
 Local authorities which plan to decommission the
HENRY intervention during the period of the trial
or which are not planning to run any HENRY
programmes during the trial period
Children’s centres:
 Centres which were recruited in the development
phase of the optimisation intervention (participating
in the rapid ethnography)
 Centres which are not planning to run any HENRY
programmes during the trial period
There will be no exclusions based on the demograph-
ics of children’s centres, but location will be monitored
to ensure inclusion of those with diverse social and
environmental characteristics. Randomisation will also
stratify by area-level deprivation to ensure balance be-
tween trial arms.
Recruitment and consent
Local authorities and their centres across the United
Kingdom will be identified from an existing database of
HENRY delivery sites (see Fig. 2). Those meeting the eli-
gibility criteria will be contacted by invitation letter (pos-
tal and electronic) issued jointly by the HENRY central
office and the University of Leeds. HENRY is currently
commissioned across the whole of the United Kingdom,
with most sites situated within England.
Explicit consent will not be sought. Instead, opt-out
consent will be sought at the cluster level (local author-
ities) and from the centres within each local authority.
It will be possible for centres to decline participation in
the randomisation, even if they are based within a con-
senting local authority. However, if a local authority de-
clines to take part in the trial, none of its centres will
be eligible to take part. Exclusion criteria related to fur-
ther commissioning of HENRY (local authorities) and
plans to run HENRY programmes (centres) will be self-
reported by commissioners and centres, respectively.
This opt-out method has been chosen because this is a
low-risk trial in which anonymised data will be ex-
tracted remotely. It has been advocated to promote a
simple and efficient trial design, and literature suggests
that it is acceptable to participants [45]. It also repli-
cates, as far as possible, the ‘real-life’ conditions under
which such quality improvement initiatives are usually
conducted in public health. The Leeds Institute of Clin-
ical Trials Research (LICTR) has experience in using an
opt-out approach and has found that it (1) is more
likely than opt-in methods to provide a more represen-
tative or ‘typical’ participating sites; (2) appears more
effective and efficient in promoting research participa-
tion by sites; and (3) is acceptable, provided that suffi-
cient sensitivity and safeguards are applied [46]. In this
instance, individual-/family-level consent is not re-
quired, because all patient-level data will be unlinked
and anonymous and is routinely collected by centres
and submitted to the central HENRY office. Centres
will not be asked to conduct any additional data collec-
tion from parents for the purposes of this trial. Our
parent advisory panel (patient and public involvement
group) and trial steering committee (TSC) have both
approved this process.
Local authorities and children’s centres will be given
30 days from the date on which the initial information
letter is sent to decline participation (confirmed by re-
corded delivery). Centres that opt out after randomisa-
tion will be treated as ‘withdrawn’.
Fig. 2 Recruitment/opt-out process. HENRY Health Exercise Nutrition
for the Really Young, LA Local authorities
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Unit of randomisation
Local authorities will be randomised in a 1:1 allocation
ratio (HENRY + optimisation intervention, HENRY as
standard) by a statistician at LICTR, using an algorithm
for covariate-constrained randomisation [47] to achieve
a balanced allocation between the trial arms on (1) local
authority baseline level of parental engagement with
HENRY (proportion of centres recruiting a minimum of
eight parents per programme, proportion of centres
retaining at least 75% of parents for a minimum of five
of eight sessions), (2) proportion of centres running at
least one HENRY programme in 2015, (3) size of local
authorities (number of children’s centres participating),
and (4) area deprivation (proportion of centres in the
least/most deprived quintiles as ranked by the 2015
Index of Multiple Deprivation at the Lower Layer Super
Output Area) [48]. Randomisation will be performed for
all local authorities at a single time point after baseline
data are transferred, prior to the implementation of the
intervention. All possible enumerations of allocation to
the trial arms will be generated, and an imbalance statis-
tic will be calculated for each allocation. A set of optimal
allocations which minimise the imbalance will be pro-
vided, and, in accordance with the principles of Inter-
national Conference on Harmonisation of Technical
Requirements for Registration of Pharmaceuticals for
Human Use guidance on randomness, the final alloca-
tion will be randomly selected from among this optimal
set [49]. Results of the randomisation procedure will be
sent by the LICTR statistician to the HENRY central of-
fice, which will be responsible for informing local au-
thorities of their treatment allocation.
Blinding
Owing to the nature of the intervention, it will not be
possible to blind allocation within intervention sites or
of those involved in the optimisation intervention train-
ing. Families attending the HENRY programme have
been made aware that HENRY uses data anonymously
for research, but they have not been told explicitly about
the Optimising Family Engagement in HENRY (OFTEN)
trial or whether their local authority has been assigned
to the optimisation. HENRY is coordinated by a central
team that is responsible for coordinating training and
for providing support and QA to areas that commission
HENRY. Because the HENRY central office is integral to
the delivery of the optimisation intervention, it will not
be possible to blind the HENRY central office (as it will
communicate the randomisation allocation to all those
responsible for its implementation); however, staff who
are responsible for collating data and transferring it to
LICTR will remain blinded to allocation. The chief ex-
ecutive officer of HENRY will be blinded to treatment
allocation and will not attend TSC meetings. In addition,
for the duration of the trial, the HENRY QA team have
agreed to reallocated areas that they are responsible for, so
that only one person will have contact with areas allocated
to the optimisation intervention. Other QA staff will be
aware that they have standard QA responsibility (e.g., an-
swering questions, providing encouragement, checking on
progress) for areas not randomised to the optimisation,
but will not know the details or content of the optimisa-
tion intervention. To further avoid contamination, the de-
tails of the optimisation intervention will not be published
until after the final analysis. Unplanned masking (unblind-
ing) will be monitored and reported to the TSC.
Intervention
HENRY
HENRY is an 8-week programme delivered in children’s
centres with the aim of providing parents with skills,
knowledge and confidence to support healthy lifestyles
among their preschool children and their families, in-
cluding parenting skills, emotional well-being and activ-
ity. The programme was set up in 2006 with the aim of
reversing rising trends in school entry age obesity.
HENRY is currently delivered within 32 local authorities
across England and Wales by trained health and com-
munity practitioners who undergo two stages of training
[26]. Stage 1, centre-level training, is a 2-day workshop
designed to equip centre staff with knowledge and skills
to promote and provide healthy nutrition within early
years settings and support parents to provide healthy
family lifestyles and nutrition for their families. The the-
oretical underpinning combines proven models of be-
haviour change, including the Family Partnership Model,
motivational interviewing and solution-focused support.
Stage 2, practitioner-level training to deliver the HENRY
programme to families, is provided to approximately
four practitioners per centre after completing Stage 1 to
deliver the 8-week HENRY programme. The aim of this
stage is to build parents’ skills, knowledge and confidence
to change old habits, provide healthier nutrition for their
young children, and encourage healthier lifestyles [25, 27].
Programme content includes sessions on lifestyle and eat-
ing habits (e.g., family meals), balancing healthy meals and
snacks, child-appropriate portion sizes, parenting, physical
activity and emotional well-being.
Current HENRY QA practice involves the review of
process data by dedicated individuals in the HENRY cen-
tral office with provision of written and oral feedback.
This QA will continue in both trial arms and will be
monitored. Staff delivering current QA activities will be
blinded to treatment allocation.
HENRY + parent engagement optimisation intervention
We summarise only the key features of the optimisation
intervention
in
the
trial
protocol
to
minimise
Bryant et al. Trials  (2017) 18:40 
Page 6 of 13

contamination (i.e., uptake of initiatives of the interven-
tion by local authorities randomised to the control arm)
and maintain blinding. The optimisation intervention
consists of interacting components delivered to local
authorities, children’s centres and HENRY facilitators.
It includes additional support to stakeholders, modifi-
cation of HENRY marketing to clarify perceptions of
the programme, and methods to modify the pre-
programme experience for parents. Strategies have
been developed to increase parent motivation to enrol
in HENRY and promote parent self-efficacy to con-
tinue to attend. Implementation of the optimisation
intervention will begin immediately following random-
isation. All components of the optimisation interven-
tion will be implemented within 6 months following
randomisation.
HENRY as standard
Local authorities randomised to the control arm will
continue to deliver HENRY programmes as per standard
practice.
Outcomes
Primary outcome
The effectiveness of the optimisation intervention will
be determined by comparing parent engagement in
HENRY + optimisation intervention vs HENRY alone.
The co-primary outcomes are (1) the proportion of cen-
tres enrolling at least eight parents per programme and
(2) the proportion of centres with at least 75% of parents
attending five of eight sessions per programme. Both will
be evaluated 12 months post-randomisation. The opti-
misation intervention will be deemed effective if either
the enrolment or attrition goals are met.
Secondary outcomes
Secondary
outcomes,
measured
12
months
post-
randomisation (unless stated otherwise), include some
further assessment of parent engagement to explore the
degree to which the intervention was effective. Data
from additional questionnaires which are routinely ad-
ministered by HENRY facilitators at the beginning and
end of each 8-week course will also been analysed to ex-
plore the potential impact of the optimisation on behav-
ioural outcomes, outlined below:
 Proportion of centres achieving all targets for
enrolment, attrition and parent compliance
 Parent adherence to HENRY programme content,
defined as the proportion of parents reporting an
increase of 0.5 in the daily frequency of consumption
of fruits and vegetables by children per programme
 Impact of HENRY on parenting and family health,
assessed by parent-report, including the following:
– Parenting self-efficacy (assessed via four parenting
confidence items with 5-point Likert scales,
modified from the validated Parenting Self-Agency
Measure [50]). This measure assesses the parents’
estimate of their ability to influence their child and
environment to lead to positive development,
which is a key goal of the HENRY approach. In
order for the questionnaire to be feasible to
administer as part of the service, HENRY chose to
reduce the number of items to a single scale of
parenting confidence. Internal consistency of these
items in a previous HENRY evaluation was high,
and internal consistency in this sample was high
(Cronbach’s alpha = 0.82 at baseline, 0.74 at
completion) [51].
– Eating behaviours (based on the Golan Family
Eating and Activity Habits Questionnaire [52]).
This validated measure is sensitive to change and
demonstrates high levels of reliability and validity.
HENRY facilitators routinely administer six items
related to family behaviours, included parent
report of family sitting together for meals,
watching television during mealtimes, consuming
take-out meals, consumption of home-cooked
foods, stopping eating when full and choosing
healthy meals. Individual evaluation of these
items will be undertaken because reliability for
the scale was poor when previously tested using
HENRY families (Cronbach’s alpha = 0.52 at
baseline, 0.56 at completion).
– Family activity (via a brief HENRY questionnaire
asking parents to report the frequency that
parents and children engage in exercise). This
questionnaire has been developed bespoke to use
within the HENRY evaluations and includes
parental report of their own activities that result
in breathlessness, with response categories
ranging from none to <1 h, 2 h, 3 h or >3 h.
Children’s activity is assessed using parental
report as energetic play, with response categories
ranging from none to 5–15 minutes, 20–30
minutes, 30 minutes to 1 h, or >1 h.
– Child screen time (via a parent reported using the
bespoke HENRY questionnaire). This assesses use
of televisions, DVDs, computers, smartphones,
and so forth with response categories ranging
from none to <1 h, 1–2 h, 2–3 h, or >3 h.
– Intake of key indicator foods per day (assessed via
14 items from a modified validated Food
Frequency Questionnaire [53] completed in
relation to the parent and child). Parents are
asked to estimate how often (never, once per
month, once per fortnight, 1–7 days per week)
they consumed each of the 14 items or groups of
Bryant et al. Trials  (2017) 18:40 
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foods (e.g., fresh fruit, sweets, chocolate, water),
with space to report the number of times
consumed. It has previously demonstrated
sensitivity to change with parents attending
HENRY sessions [25].
 Longitudinal impact of HENRY + optimisation
intervention vs HENRY alone (parent engagement
[enrolment and attrition] within centres during the
12-month follow-up in local authorities which
provide data for more than one programme per
centre at follow-up) (This evaluation will explore
whether the optimisation intervention needs time to
‘bed-in’ and/or whether any early effects are
maintained over time.)
Process evaluation
A process evaluation will be conducted by an LICTR re-
searcher in accordance with MRC guidance on evaluat-
ing process in complex interventions [19]. In brief, the
aims of this evaluation will be to (1) examine the uptake,
delivery and acceptability of the optimisation interven-
tion across local authorities/children’s centres (reach);
(2) explore the effects of individual intervention compo-
nents at increasing parent engagement, along with po-
tential unintended consequences; and (3) consider the
utility of theories underpinning the intervention and ap-
proach used to develop the intervention design. Process
measures
will
include
quantitative
measurement
of
centre uptake and fidelity of delivered trial components;
qualitative
and
quantitative
analysis
of
stakeholder
perceptions of intervention components considering
individual, organisational and contextual factors; quanti-
tative measurement of enrolment methods used to re-
cruit HENRY programme participants; and qualitative
and/or quantitative measurement of predicted behaviour
change outcomes among stakeholders targeted in the
implementation optimisation. Quantitative data required
for process evaluation will be gathered and reported on
paper case report forms by a researcher within the
LICTR, who will also collect qualitative data from a ran-
dom selection of sites in person, including interviews
and observations.
Economic evaluation
Economic evaluation will model the benefits of optimisa-
tion intervention over the costs of implementation and
will seek commissioners’ willingness to pay for this. It
will include the costs required to deliver the intervention
(gathered and transferred from HENRY) and the rou-
tinely collected outcome data.
The cost-effectiveness analysis in the present trial will
include an array of trial endpoints (including parent en-
rolment and attrition rates) and costs. Cost-effectiveness
acceptability curves will describe the probability that the
optimisation intervention is cost-effective for a range of
maximum monetary values that a decision-maker might
be willing to pay for a particular unit change in outcome.
Cost-effectiveness analysis leaves it to decision-makers
to form their own view of the relative importance of
these results [54]; therefore, in a second part of the
work, we will conduct a meeting with commissioners to
determine their willingness to pay per additional unit of
effectiveness (parent engagement) before concluding
whether the optimisation intervention can be considered
cost-effective. We will use contingent valuation tech-
niques and design an experiment to estimate the point
at which commissioners consider that the costs of the
programme are acceptably offset by the benefits of en-
gaging effectively with parents.
Sample size
We assumed that 25% of the 32 local authorities cur-
rently running HENRY will not be eligible or will opt
out of the study, leaving 24 local authorities (12 per
arm). Power calculations for this fixed sample size (with
all eligible centres in the United Kingdom invited to take
part) were therefore conducted to examine anticipated
power for various intervention effects, at the 5% signifi-
cance level, in each of the primary outcomes and for the
composite endpoint (enrol at least eight parents per
programme and retain ≥75% of parents attending five of
eight sessions) (see Table 1 for scenarios). On the basis
of data from previous HENRY programmes (all terms in
2014), we assumed an average of 6 children’s centres per
local authority providing a total of 144 children’s centres
(72 per arm), an intra-cluster correlation coefficient
(ICC) between 0.05 and 0.1, a coefficient of variation in
cluster size of 0.54, and the following estimates of the
outcomes in the control sites (HENRY alone): 55% of
centres will enrol at least eight parents per programme;
50% of centres will retain ≥75% of parents attending five
of eight sessions; and 25% of centres will enrol at least
eight parents per programme and retain ≥75% of parents
attending five of eight sessions. Thus, with the antici-
pated number of centres (24 local authorities, 144 chil-
dren’s centres), we will have at least 80% power to detect
meaningful improvements in differences of between 25%
and 30% in either of the primary endpoints or the com-
posite endpoint at the 5% significance level, assuming
the ICC is no greater than 0.05.
Data collection and transfer
In this trial, we will use routinely collected data for all
primary and secondary outcomes, except for the process
evaluation data, which will be gathered by an independ-
ent LICTR researcher. HENRY has designed a centra-
lised process for evaluating programmes, developed for
QA purposes and reporting to commissioners of the
Bryant et al. Trials  (2017) 18:40 
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service. For the purpose of this trial, baseline data at the
centre level include routine data on enrolment and at-
tendance at programmes that have been run before
randomisation. These data also include anonymous
information on participant satisfaction, parent-reported
compliance, parenting and family lifestyle (Table 2), which
are gathered in questionnaires on the first and last days of
each HENRY programme. This information is submitted
to the central HENRY office (without any personal iden-
tifiers for the families), which check the data for complete-
ness and collate the information in a.csv file.
For the trial period, centre-level baseline data from the
most recent programme delivered prior to randomisa-
tion (winter term 2015) will be used. Follow-up data will
be gathered 12 months after randomisation. It will in-
clude routine data collected from the autumn and spring
terms (2016–17), allowing 6 months for intervention de-
livery at all sites followed by the delivery of two terms of
HENRY programmes. In accordance with the planned
intention-to-treat (ITT) analysis, data will be collected
from centres that are not compliant with the interven-
tion. For those withdrawing from the trial, only data col-
lected up to the point of withdrawal will be used.
All data transferred from HENRY to the LICTR will be
in the form of unlinked, anonymised datasets and will be
transferred via a secure, encrypted system. Only data for
centres participating in the trial will be transferred. Data
transfer agreements (including details on the sender, re-
cipient, content of transfer/general purpose of transfer
and any data-processing limitations) will be set up be-
tween HENRY and the LICTR prior to the transfer of
any data. Queries pertaining to outliers or missing data
will be sent to HENRY in accordance with LICTR stand-
ard operating procedures. Any new data that are identi-
fied following queries will also be transferred via the
secure, encrypted system. Missing data, except individual
data items collected via parent questionnaires, will be
chased until it is received, confirmed as not available, or
the trial is at analysis. For missing item-level data within
questionnaires (item non-response), no attempts will be
Table 1 Power calculations for enrolment and attrition endpoints
for various estimates of the intervention effect and a fixed sample
size of 144 children’s centres in 24 local authorities
Outcome in
the control
Percentage point increase
in intervention
Power for
ICC = 0.1
Power for
ICC = 0.05
Enrolment (≥8 parents per programme)
55%
5%
6%
7%
10%
15%
18%
15%
29%
35%
20%
49%
58%
25%
70%
79%
30%
87%
93%
Attrition (≥75% of parents attending five of eight sessions)
50%
5%
6%
7%
10%
15%
17%
15%
28%
34%
20%
47%
55%
25%
67%
76%
30%
84%
91%
Enrolment and attrition (at least eight parents per programme and 75%
of parents attending five of eight sessions)
25%
5%
7%
8%
10%
17%
19%
15%
31%
37%
20%
49%
58%
25%
67%
76%
30%
82%
89%
ICC Intra-cluster correlation coefficient
Table 2 Data collection summary
Data
Screening
Randomisation
Baseline
On-going
Follow-up
Local authority level
Cluster eligibility
X
Stratification factors
X
Programme enrolment
X
X
Programme attrition
X
X
Implementation data (e.g., fidelity)
X
Parent level (anonymised routine)
Infant diet (fruit and vegetable intake)
X
X
Family habits and lifestyle
X
X
Implementation/process data
X
Intervention level
Costs for intervention delivery for economic evaluation
X
X
X
X
X
X indicates when data are gathered
Bryant et al. Trials  (2017) 18:40 
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made to retrieve missing data; only missing question-
naires will be chased.
All data provided will be stored, handled and processed
in accordance with the principles of the 1998 Data Protec-
tion Act, the operation of the agreement and the study
publication policy. The rights for this data belong to the
study sponsor, and no processing, including further data
transfer in whole or in part to a third party, is permitted
other than as stated in the data transfer agreements.
Analysis
Statistical analysis of the quantitative elements of the
trial is the responsibility of the LICTR statisticians. The
analysis plan outlined in this section will be reviewed,
and a detailed statistical analysis plan will be written and
approved, before any formal analyses are undertaken.
Statistical analyses will be carried out by the ITT
principle, and statistical significance will be assessed at
the two-sided 5% significance level. The ITT population
is defined as analysis according to the randomisation
and regardless of compliance with the protocol or with-
drawal from the trial.
Primary analysis
The primary outcomes associated with enrolment or attri-
tion will be compared between the intervention and con-
trol arms through a cluster-level analysis, using a weighted
t test of cluster-level proportions and a two-stage process
to adjust for covariates [55]. Intervention effects and
corresponding 95% confidence intervals will be presented.
As part of a sensitivity analysis, the reliability of random
effects logistic regression will also be investigated.
In the primary analyses, missing data will be assumed
to be missing completely at random; that is, analyses will
be performed using complete cases (including those
where sufficient item-level data exists). The extent of
unit non-response (data missing from a whole course)
will be assessed, and the reason for missingness and the
missing data mechanism will be investigated.
A sensitivity analysis accounting for all participants in
the ITT population assuming data missing at random,
using multiple imputation, will be performed, and poten-
tial predictors of missingness will be investigated. The
number of imputations will be determined using Bodner
rule of thumb, where number of imputations is similar
to the percentage of cases that are complete [56].
Secondary analysis
Adherence to HENRY programme content and the im-
pact of the HENRY optimisation on parenting and fam-
ily health will be analysed using a cluster-level analysis
of either proportions or means, depending on the out-
come, as described for the primary analysis. As part of
sensitivity analyses, the degree of clustering at each level
of the data structure, and the reliability of two-level (par-
ents nested within centres or local authorities) and
three-level (parents nested within centres within local
authorities) random-effects models will also be investi-
gated. The proportion of centres achieving combined en-
rolment, attrition and parent adherence will be analysed
using the same methods described for the primary out-
comes. The longitudinal impact of the intervention on
parental engagement will be analysed among those local
authorities providing data for more than one programme
per centre at follow-up, using logistic regression with
random effects adjusting for the time point of the
programme.
Appropriate scoring manuals will be followed, and
missing items within individual outcome measures will
be treated according to instructions for that particular
measure. For all other outcomes (without instructions
for dealing with missing data), half rule will be used,
substitution of the mean of the answered questions for
that specific subscale for the missing responses as long
as at least half the questions are answered [57]. If more
than 50% of the items are missing, the outcome will be
assigned as missing.
Data monitoring
Trial supervision includes a core project team, a study
management group, and a TSC. The core project team
will comprise the chief investigator and a research assist-
ant, with oversight from all other monitoring groups.
The study management group will comprise the chief in-
vestigator, clinical trial research unit team (research as-
sistant
[WB],
statisticians
[BC
and
MC],
data
management, trial management [SH] and health econo-
mist [ST]). The TSC will comprise an independent chair
(a professor of chronic disease and public health) plus
independent
expertise
in
statistics,
qualitative
and
mixed-methods research, behaviour change and a parent
(a volunteer from our parent advisory group). Because
the trial is using routine data, a separate data monitoring
and ethics committee was not convened. Rather, the in-
dependent TSC will adopt a safety monitoring role, and
will establish a subcommittee to review safety issues
should this become necessary. Serious adverse events
are not anticipated, and, as such, a separate protocol for
unmasking has not be produced. This will, however, be
reviewed by the TSC as a regular item on the meeting
agenda.
The TSC operates in line with the LICTR terms of ref-
erence as amended and agreed by TSC members at their
first meeting. Data provided to the LICTR will be moni-
tored for quality and completeness by the LICTR, using
established verification, validation and checking pro-
cesses. Clinical governance issues pertaining to all as-
pects of routine management will be brought to the
Bryant et al. Trials  (2017) 18:40 
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attention of the TSC and, where applicable, individual
local authorities.
Trial organisation and administration
The trial is sponsored by the University of Leeds and co-
ordinated by the LICTR (University of Leeds). The man-
agement group consists of the chief investigator and the
study management group. Protocol amendments will be
handled in accordance with LICTR standard operating
procedures. Amendments required to the protocol and
ethically approved documents will be identified by the
trial researcher and the chief investigator. Amendments
will be drafted and reviewed by members of the study
management group and sponsor as appropriate. Sub-
stantial amendments to ethically approved documents
will be submitted to the School of Medicine Research
Committee for ethical opinion prior to implementation.
A list of amendments will be included in the final
report.
Dissemination plan
A full dissemination plan will be written in accordance
with those agreed by the funders. This includes dissem-
ination to all stakeholders, including parents, and will be
supported by our parent advisory group. The dissemin-
ation plan and publication plan will be developed by the
study management group and agreed by the TSC. The
policy will detail appropriate methods for determining
writing groups, lead authors standard acknowledgement
text to be included and necessary funding disclosure.
The publication plan will detail potential paper titles
(main findings and additional papers), authors (highlighting
lead author) and time lines. Health Research Authority
guidance for informing participants of the trial results will
be applied [58].
Discussion
Engaging parents to enrol and attend programmes to
prevent obesity in their children’s early years is a chal-
lenge. This resounds with literature exploring the diffi-
culties of recruiting parents to attend population-based
programmes in the absence of health problems in their
children [9, 30]. Early childhood provides an opportunity
to intervene to establish healthy behaviours that are crit-
ical for optimum growth and development [7], but the
failure to attract parents to programmes such as HENRY
(particularly in populations theorised to have the great-
est benefit) is a threat to the success and viability of such
programmes. Our work has developed a theory-based
intervention specifically targeting parent engagement
with HENRY, with clear, transferable components for
community-based interventions delivered to parents of
young children. The early-phase evaluation of this opti-
misation intervention is described here, including methods
to estimate the willingness of commissioners to pay for
any additional costs borne by additional engagement
activities. Ultimately, the true value of the optimised
intervention will be ascertained following these discussions
with the commissioners.
Implementation research is usually focused on the im-
plementation of interventions of known effectiveness
into routine practice and policy [23]. However, we in-
tend to evaluate an approach to optimising the imple-
mentation of HENRY prior to a further evaluation of its
clinical effectiveness. This approach is relatively novel
and follows literature suggesting that complex interven-
tion components should ideally be optimised and tested
in evidentiary research [24]. Such an approach ensures
that the future clinical effectiveness data relate to the
impact that interventions can have once components
have been enhanced. Similarly to other interventions
(particularly prevention programmes), we recognised a
need to increase parent engagement to enrol and attend
HENRY programmes in order to improve the chances of
a more successful, cost-effective definitive trial of clinical
effectiveness. However, other components within com-
plex interventions, such as content or delivery aspects,
could warrant optimisation prior to effectiveness testing.
A future pilot RCT is planned to test the feasibility of
conducting a definitive trial of the effectiveness of
HENRY to prevent childhood obesity (also within the
National Institute for Health Research [NIHR] under
Career
Development
Fellowship
CDF-2014-07-052).
This will occur regardless of the outcome of the present
optimisation trial because there remains a need to estab-
lish an evidence base of an intervention that is already
widely commissioned.
Trial status
Recruitment and randomisation of local authorities is
complete. Implementation is on-going and family enrol-
ment (providing data on enrolment and attendance to
the HENRY programme) was started in September 2016
and will continue until April 2017.
Abbreviations
COM-B model: Capability, opportunity and motivation; cRCT: Cluster
randomised controlled trial; HENRY: Health Exercise Nutrition for the Really
Young; ICC: Intra-cluster correlation coefficient; ITT: Intention to treat;
LA: Local authorities; LICTR: Leeds Institute of Clinical Trials Research;
MRC: Medical Research Council; NIHR: National Institute for Health Research;
OFTEN: Optimising Family Engagement in HENRY; QA: Quality assurance;
RCT: Randomised controlled trial; TSC: Trial steering committee
Acknowledgements
We acknowledge our parent advisory team for their support in developing
the intervention and ongoing advice in study design and recruitment (Amal
Najlat, Chloe Anderson, Kelly Milner, Claire Donkin, Sarah Young, Terri Francis
and Rachael Baptista). We thank members of the trials steering committee
(TSC), including Professor Peymane Adab (TSC Chair, University of
Birmingham), Professor Alicia O’Cathain (mixed methods expert, University of
Sheffield), Professor Kelvin Jordan (statistical expertise, Keele University), Dr
Bryant et al. Trials  (2017) 18:40 
Page 11 of 13

Thomas Willis (behaviour change expertise, University of Leeds) and Amal
Najlat (parent representative). We are also grateful to the children’s centres
that permitted observations which support the intervention development
(anonymous). We acknowledge the optimisation intervention development
team for their significant contributions (Professor Pinki Sahota, Dr Maureen
Twiddy, Jackie Moores and Chloe Anderson). We thank the HENRY team for
their support in developing and delivering the intervention, providing data
and liaising with centres (Rebecca Nourse, Sian Livsey and Kim Roberts).
Funding
The trial is funded by the NIHR Trainees Coordinating Programme awarded
to the chief investigator (MB) (CDF-2014-07-052). The views expressed are
those of the authors and not necessarily those of the NHS, the NIHR or the
Department of Health.
Availability of data and materials
Not applicable.
Authors’ contributions
MB and JS conceived of the study. MB secured funding with support from
JN, AJF, JS, JB, RF and HR. WB, KR, JB and MB participated in the design of
the intervention and the development of the recruitment strategy. All
authors contributed to the design of the trial. BC, AJF, JB, MB, MC and SH
advised on the statistical design and sample size calculation and also
developed the recruitment strategy. ST led the economic evaluation design.
All authors contributed to the writing of the manuscript and prepared a
draft manuscript. All authors read and approved the final manuscript.
Authors’ information
Not applicable.
Competing interests
KR is the chief executive of HENRY, which may receive increased publicity
and consequent commissioning as a result of this research. KR is blinded to
treatment allocation and is excluded from steering committee meetings.
Involvement of KR was essential for the development of the optimisation
intervention under investigation (ensuring feasible approaches were
recommended and agreeing on related incurred costs). HR is supported by
the NIHR Collaboration for Leadership in Applied Health Research and Care
(CLAHRC) North Thames at Barts Health NHS Trust. The other authors declare
that they have no competing interests.
Consent for publication
Not applicable.
Ethics approval and consent to participate
This study was approved by the School of Medicine Research Ethics
Committee at the University of Leeds (MREC15-017).
Author details
1Leeds Institute of Clinical Trials Research, University of Leeds, Leeds LS29JT,
UK. 2Department of Nutrition, Gillings School of Public Health, University of
North Carolina, Chapel Hill, NC 27599, USA. 3Department of Epidemiology,
Gillings School of Public Health, University of North Carolina, Chapel Hill, NC
27599, USA. 4HENRY Head Office, 8 Elm Place, Old Witney Road, Eynsham
OX29 4BD, UK. 5Academic Unit of Primary Care, Institute of Health Sciences,
University of Leeds, Leeds LS2 9JT, UK. 6London School of Hygiene and
Tropical Medicine, 15-17 Tavistock Place, London WC1H 9SH, UK. 7Academic
Unit of Health Economics, Leeds Institute of Health Sciences, University of
Leeds, Leeds LS2 9JT, UK.
Received: 27 April 2016 Accepted: 27 November 2016
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