Methodological development of an exploratory randomised controlled trial of an early years' nutrition intervention: the CHERRY programme (Choosing Healthy Eating when Really Young)

Engagement with local stakeholders

A key practical measure in the development of any community‐based intervention is engagement with local stakeholders to understand the local context and to consult on the nature of the proposed intervention. Members of the study team in both study sites (Islington and Cornwall) visited a wide range of key local stakeholders based in local authorities, community health services and voluntary sector organisations. In particular, a major effort was made to engage with children's centre staff in both areas to understand more fully what was currently happening in terms of nutritional support provided and the potential for developing a new intervention. Local steering groups comprising representatives of the different sectors were formed in both areas to provide an ongoing consultation forum during the development and implementation stages of the study.

Understanding the nature of the problem and options for support

A mixed‐methods approach using both qualitative and quantitative techniques was used to explore with parents/guardians and children's centre staff factors influencing young children's diets, barriers to change and options for developing a supportive intervention. Initially, separate focus groups with parents/guardians and staff were conducted in both areas (Hayter et al. 2012). A questionnaire survey was conducted with heads of all children's centres in both locations as well as over 260 parents/guardians using opportunistically selected children's centres to inform the development of the intervention (Ohly et al. 2012). A short self‐administered questionnaire was also used to gather information from children's centre managers on food‐related activities taking place, options for staff training and nature of food policies operating in each centre.

The detailed results from this preliminary work have been published elsewhere (Hayter et al. 2012; Ohly et al. 2012) but in summary the main insights gained to inform the development of the intervention were:

1. Acknowledgement of the wide range of factors influencing parental feeding practices including:
   1. Affordability of food,
   2. Time constraints in hectic family life,
   3. Availability of foods and influence of food marketing and advertising,
   4. Family influences and challenges to parental wishes and
   5. Familiarity of food to children and the difficulties of dealing with fussy eating.
2. Key implications for development of intervention were:
   1. Recognition that complex and varied influences on food practices require multifaceted support. Information leaflets alone would not be sufficient to address problems identified.
   2. Need to understand importance of family and social influences within family structures.
   3. Strong support expressed from both parents and staff for the development of a new tailored intervention in children's centres.
   4. Necessity of practical support that engages with parents and equips them with the necessary knowledge, skills and self‐confidence and moves beyond narrow provision of information alone.
   5. Need to include support on dealing with fussy eating and managing on a tight budget.
   6. Very few differences were evident on support required in urban and rural settings – core programme therefore applicable in both areas.

Identifying the evidence base

A detailed and comprehensive review of the relevant UK and international nutrition, health promotion and behaviour change literature was undertaken to assess the evidence base for the intervention. Particular focus was placed upon interventions targeting pre‐school children and those delivered in early years settings. Both systematic reviews (n = 6) and empirical studies (n = 20) were included in the review. In addition, a review was also undertaken of studies, which had assessed the factors influencing dietary patterns of families with pre‐school children and barriers preventing the adoption of recommended feeding practices.

The review highlighted the paucity of well‐designed community‐based early years' nutrition interventions but usefully highlighted the importance of the following issues:

1. Methodological limitations of literature included poor designs, small and mostly unrepresentative study samples and poor evaluation with limited follow‐up data. Need for more robust dietary assessment pre‐ and post‐intervention.
2. Limited inclusion of lower income populations.
3. Most successful studies achieved increases in fruit consumption and used a variety of approaches including parental support.
4. Encouraging results also from repeat exposure studies tackling fussy eating habits.
5. Few UK studies published.
6. Very limited focus on intervention to reduce sugary drinks or snack consumption.

Selecting a theory base for the intervention

It is now increasingly recommended, not only by the MRC 2008 guidance, but also by other reports that theory should be used in the design and evaluation of public health interventions (Medical Research Council 2000, 2008; National Institute for Health and Clinical Excellence 2007). It is argued that an intervention based on relevant theory rather than just a pragmatic approach is more likely to be effective (Medical Research Council 2008). Theory should also be used to provide a rationale for how an intervention will achieve the desired changes. In the context of this study, two levels of change were anticipated (at the individual and also institutional level, i.e. the children's centres) requiring a wider theoretical perspective.

However, despite this growing emphasis on the use of theory in developing interventions, there is little practical guidance on just how to select an appropriate theory (Michie et al. 2005). For instance, the MRC recommends using an appropriate theory with little explanation of what this means (Medical Research Council 2008); NICE similarly recommends choosing a ‘relevant behavioural model’ (with a further complication here in that the terms theory and model are sometimes used inter‐changeably; National Institute for Health and Clinical Excellence 2007). The philosopher John Dewey in a classic seminal paper noted back in 1916, the means by which particular theories are selected and used, often remains in the ‘twilight zone of enquiry’ (Dewey 1916). We therefore wished to formulate an explicit and transparent procedure by which we carried out the identification of appropriate theories to inform the development of the early years' nutrition intervention.

Information gathered from the earlier stages of the study provided useful background to inform the selection of the theory base. In particular, critically reviewing recent systematic reviews of the behaviour change literature helped to identify common findings on the theoretical basis of interventions. From this, we then put together a composite approach drawing on Carpiano and Daley's (Carpiano & Daley 2006) recommendations in using and building theory in the context of public health, supplemented by guidance from NICE (National Institute for Health and Clinical Excellence 2007) and the GSR review (Darnton 2008), both of which set out a structured approach to developing interventions for behaviour change. Carpiano and Daley outline a three‐stage approach to using theory that we then followed with modification:

1. Define a conceptual framework to identify the variables and the broad relations between them that account for the phenomenon of interest.

   This is equivalent to the NICE guidance and the ANGELO (Analysis Grid for Elements Linked to Obesity) approach that involves mapping the problem or issue to be assessed and where the best options for intervention might lie (Swinburn et al. 1999; National Institute for Health and Clinical Excellence 2007).

2. Select and define relevant theories to provide a more dense and coherent set of relationships between the key variables of interest.

   To do this and to identify specific causal factors, the baseline qualitative and quantitative data were used to identify the key influencing factors and also those that could be addressed in the context of intervention.

3. Finally, develop a logic model that is more specific still and that predicates specific assumptions about a limited set of outcomes.

   We set about designing a logic model in relation to the study outcomes (see Fig. 2).

   

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   Figure 2

   Logic model for the development of CHERRY.

Lastly, based upon the essential criteria of relevance and effectiveness (Taylor et al. 2006), we selected two theories: the social cognitive theory (Bandura 1986) to inform the individual behaviour change components of the intervention and the stage theory of organisational change for the institutional element (Kaluzny & Hernandez 1988). The social cognitive theory highlights the importance of self‐efficacy in behaviour change. The qualitative data collected in the focus groups stressed that parents were largely well informed on dietary recommendations but often lacked the skills and confidence to adopt practically these measures in their busy and hectic lives (Hayter et al. 2012). The stage theory of organisational change, based on Rogers' theory of innovation (Rogers 1983), describes how organisations pass through a series of steps in the process of implementing innovation and change. Again, both the qualitative and quantitative data collected from children's centre staff highlighted the importance of policy guidance, staff training and engagement with parents as key issues in promoting change in nutrition practices within the children's centres (Hayter et al. 2012; Ohly et al. 2012).

Study setting: children's centres

Children's centres provided the setting for recruitment of families and delivery of the intervention. Children's centres are government‐funded early years organisations where children under five and their families can receive integrated services and support, such as access to health and parenting services, advice and information on health, training and return to work, and in some areas high‐quality early years child care (Department for Education 2012).

Selection of children's centres

Children's centres in both study locations were randomly selected to participate in the study. Initially, 64 centres in total were approached with 38 agreeing to participate. More children's centres were selected in Cornwall to represent its larger geographical area and population size; in Islington, six children's centres were simply randomly selected from a list of those centres who expressed an interest in participating in the study (9 out of 16). In Cornwall, the random selection was stratified by geographical location and deprivation to ensure representativeness of the county. Ten children's centres were selected from those who expressed an interest in participating in the study (30 out of 33). The 16 selected children's centres were then randomly assigned to intervention or control group. Three intervention and three control centres in Islington, and five intervention and five control centres in Cornwall.

Sample size

For exploratory trials, it is inappropriate to undertake a detailed power calculation; one of the main purposes behind conducting a pilot study is to assess practicality and acceptability of the trial methods and to provide an effect size and intra cluster correlation coefficient to inform power calculations for a future definitive trial (Medical Research Council 2008). However, based upon pragmatic considerations, it was estimated that in each children's centre (n = 16), there would be approximately 40 possible participants. Assuming 60% of parents invited to participate accepted the offer, and that at the 6 months follow‐up there would be a 75% retention rate, this would give a final sample of 288). This target sample is very similar to a successful primary care nutrition intervention which had a sample size of 258 families at follow‐up (129 per arm; Ashfield‐Watt 2007). That trial was designed to have at least 80% power at the 5% significance level, in order to detect an increase of 0.7 portions of fruit and vegetables per day (standard deviation 2.0).

Recruitment of subjects

Parents were recruited into the study over five recruitment waves between September 2010 and November 2011. Parents were eligible for inclusion if they had at least one child aged between 18 months and 5 years at the time of recruitment. For parents with more than one child in this age range, the youngest child was chosen for assessment. Parents were excluded from participation if their child had a diagnosed medical condition, which affected their diet, for example food allergies or diabetes, and if they were not able to communicate effectively in English.

Parents were recruited using a variety of different approaches to maximise uptake. Researchers provided induction sessions at the children's centres, during which they explained the project fully and asked staff to identify suitable families. Local health visiting teams and other outreach staff were also asked to refer families to the study. Researchers regularly attended outreach sessions at children's centres and other local childcare settings (such as community groups, primary schools and private nurseries) to meet suitable families. The researcher gave a brief explanation of the study, assessed eligibility and invited parents to take part. Eligible parents registered their details and were then followed up with a telephone call from the research team to arrange their initial home visit.

In addition to face‐to‐face recruitment, adverts were also placed in local newspapers, and schools, libraries and doctors' surgeries were asked to display recruitment posters. Fliers were distributed by post to families who were registered with children's centres. Social networking sites were also used to increase awareness of the project.

Finally, communication technology was also used as a recruitment tool. Adverts for the project included a ‘short‐code’, a 5‐digit number to which parents could text ‘CHERRY’ to register their interest. They immediately received an automated acknowledgement message. All participants who registered their interest by this method were telephoned by the research team within 24 h in order to explain the intervention more fully and assess their eligibility to participate. All parents that took part were offered a £10 high street voucher and a cook book developed for families with young children on completing the follow‐up assessment after 6 months.

Development of the intervention

The CHERRY programme was developed by the research team between June 2009 and August 2010 based upon the data gathered in the initial stage of the study. It was a family‐centred nutrition intervention delivered in selected children's centres across Islington and Cornwall. The programme focused on healthy eating for under‐fives and their families and involved a mixture of learning, discussion and practical ‘cook and eat’ activities. The training of children's centre staff and support with developing food policies in centres was also a key component of the intervention.

Informed by the earlier stages of the study, and in particular the qualitative and quantitative data gathered from parents (Hayter et al. 2012; Ohly et al. 2012), the focus of CHERRY was on making simple changes to improve the food that young children and their families eat. Specifically, it aimed to increase fruit and vegetables and to decrease the amount of sugary drinks and snacks consumed by young children. It also aimed to help parents gain confidence around food, increase their food involvement and their own consumption of fruit and vegetables.

Delivery of the intervention

CHERRY was delivered by trained tutors to eight groups of families in Islington and 12 groups in Cornwall between October 2010 and November 2011, with an average of eight (and between 5–12) families attending each group. Tutors were selected according to their ability to successfully deliver the CHERRY programme; they were then trained to deliver the programme during a 1‐day intensive training course, which all tutors attended. The research team monitored the tutors for consistency and quality of delivery by attending sessions at random throughout the course of the project. At each session, a member of staff from the children's centre (and/or sometimes one of the research team) was present to provide support to the tutor as required. The delivery was standardised as much as practically possible between groups; however, there were some differences depending on the needs of each group, for example, the recipes prepared and the focus of discussions.

The intervention group participants attended four sessions (one each week) over 4 weeks. Each session lasted 2 h. The first hour of each session involved parents discussing and learning about a variety of aspects of healthy eating while the children attended a free crèche in the adjacent room (the crèche activities were not considered part of CHERRY and were not monitored). The second hour involved parents and children together for a more practical, ‘hands on’ cook and eat session involving basic food preparation and tasting. Each session began with a recap from the previous week and finished with parents being given a ‘CHERRY at home’ activity to complete before the following week's session; these were both designed to consolidate parents' learning. The intervention group also received SMS reminders via mobile phones between sessions; SMSs included the main messages of the CHERRY programme, as well as reminders to attend each session. Table 1 outlines the content of the course in more detail.

Other intervention components

A major limitation of many interventions is the failure to focus on improving the social environment, which has a profound influence in supporting and maintaining individual behaviour change (National Institute for Health and Clinical Excellence 2007). Therefore, the intervention comprised not only individually focused nutrition support, but also encompassed activities directed at developing the capacity of the children's centre to promote and maintain healthy nutritional practices. In the intervention centres, a staff training session was offered to all staff working in the centres. The training session covered various aspects of healthy eating and nutrition for early years and included an introduction and overview of the CHERRY programme. Each training session was tailored to the needs of the staff, as identified by heads of each intervention centre. Intervention centres were also given support and advice to revise and develop their centre's food policies in order to support healthy eating practices and procedures.

Secondary outcomes

The secondary outcome was the child's soft drink consumption. This was defined as the total quantity (mL) of soft drinks consumed; the number of occasions soft drinks were consumed; the types of soft drinks consumed; the quantity (mL) of each type. Sugary drinks and artificially sweetened drinks were considered separately.