In total, 51 participants took part in the nested study from three local authorities, including nine parents across two focus groups in the pilot work and four parents from two focus groups within the feasibility study (Table 1).
Table 1
Data collection | n | Description (including recruitment source) |
| | Pilot phase recruitment | Feasibility study recruitment |
Focus groups | | | |
Parents | 13 | 4 x attended HENRY; 5 x did not attend HENRY | 3 x control; 1 x intervention |
Interviews | | | |
Parents | 16 | - | 7 x control; 9 x intervention |
Staff | 15 | 2 x HENRY centres | 4 x control; 4 x intervention 5 x control and intervention |
Managers | 7 | 1 x HENRY centre | 2 x control; 1 x intervention 3 x control and intervention |
There was representation from both treatment arms (HENRY/ non-HENRY in pilot work) for staff (control: 26.7%, intervention: 40%), managers (control: 25%, intervention: 37.5%) and parents (control: 52%, intervention 48%). A number of the staff (33.3%) and managers (37.5%) were found to work in both control and intervention centres. Focus groups lasted on average 45 minutes, and interviews lasted on average 22 minutes.
Staff And Manager Perspectives
Staff appeared to pose the greatest risk of contamination within the feasibility study, mainly through face-to-face encounters, and less commonly through promotion of HENRY (social media and posters in centres). Staff working across multiple children centres, including both control and intervention centres, appeared to be key contributors to contamination within the feasibility study. This situation was a commonly reported and considered to be a positive way of sharing staff and knowledge. While one manager reported that staff at their centre made a conscious effort not to share the information learnt at their HENRY feasibility study training:
“They have been very mindful not to share anything of HENRY when they are at the other site. So they have made a conscious effort not to do that” (Manger, control & intervention centre), it was acknowledged, that it was difficult not to incorporate the HENRY messages into everyday practice once learnt: “its hard because you can’t lose the learning that you have got can you?” (Manger, control & intervention centre).
Further, some staff also discussed how they would purposely incorporate HENRY messages into other programmes that they delivered as they felt that it would benefit parents, for example HENRY messages about portion sizes: “…the portion sizes, that’s obviously shared with the other centres as well, cos [because] it is really important cos the portion size of children was quite large. So we have embedded those kind of…in the other programmes as well.” (Staff, control & intervention centre).
Staff meetings at the district level presented further potential for contamination, as we learnt that staff from a number of centres met to discuss best practice and share ideas: “Although we work in different centres we all meet up every month for a full team meeting, we talk about what's going on in centres and it [HENRY] could be mentioned there.” (Staff, intervention centre).
Some children centre staff reported sharing HENRY messages at team meetings as they perceived it as helping others: “Yes obviously we have our health forums, our start well forums and things like that. Some of them haven’t even started HENRY. So giving that information out that is really useful for them.” (Staff, control and intervention centre).
Staff in the centres delivering HENRY also reported personally implementing behaviour change based on what they had learnt from attending HENRY training: “And like I say we practice what we preach and try and be a role model and we have healthy snacks, healthy things in our fridge and it makes us think more about what we are eating and the benefits to us of healthy eating and giving you more energy during the day because when you are doing owt [anything] you need more energy that you think. I think on the whole it’s had an impact on everybody. Everybody has opened their eye to like adapting things from HENRY into our daily lifestyle.” (Staff, intervention centre).
These behaviours may have been observed by parents attending centres, but the degree to which this could influence parental behaviours is uncertain.
Contamination occasionally occurred through the promotion of the HENRY programme to parents and via sharing of healthy messages that were learnt through attending HENRY training. This was variable. For example, a manager in one of the local authorities reported that centres did not use social media to share healthy advice, whereas the another manager from the other local authority admitted to using it for this purpose: “We have Facebook, so we use Facebook and our worker who puts on Facebook, she will put out a message once a month or something.” (Manager, control & intervention centre).
Most intervention centres reported that they advertised the HENRY programme using posters and display boards. Whilst the feasibility study attempted to limit this to intervention centres only, displays could be observed by any parents visiting from other centres:
“We have things like the HENRY display out. We have all the books… we have displays about portions and things like that. So really it’s all over the place. Sometimes they don’t even known [laughter] you’re telling them. It’s stuff they pick up” (Staff, Intervention centre).
Parent Perspectives
Parents appeared to present a smaller risk of contamination compared to children’s centre staff and managers. Control parents who were interviewed had limited knowledge about the HENRY programme prior to being recruited into the feasibility study: “Just that it was to do with healthy eating for the child and also the mother that was the brief I got from it.” (Parent, control centre).
Parents did not report investigating the HENRY programme or finding out more information; however, a small number did report that they changed their behaviour due to being recruited into the study and knowing that they would be weighed at follow up:
“Yeah I am now much more stricter on my diet than I was before. I try to because everybody wants to be happy with their weight.” (Parent, control centre)
Parents suggested that their choice of which children’s centre to attend was based predominantly on the distance that they had to travel. The majority said that they usually attended just one centre (thus reducing the potential of knowledge transfer between centres); however, a small number of parents also visited other centres or knew of others who attended multiple centres:
“…….. if you aren’t close it makes it very hard for parents to be able to attend. I think having knowledge of different children's centres that are also running the HENRY programme it might make it easier to schedule and be aware of how to get to things like that if it isn’t the centre you already go to. I think everyone that had come to our HENRY programme lived in a relatively close proximity to where we were attending” (Parent, intervention centre).
In terms of sharing of messages, parents said that, though they often discussed topics with other parents (or within other programmes provided by centres), these discussions were rarely reported to be specific to HENRY. Nevertheless, some reported conversations topics that were similar to those delivered in the HENRY programme (for example, portion size, healthy diet and physical activity):
“My friends, we have got quite a few in my friendship group that have got kids the same age. So we all kinda like share tips. Erm also, so at my daughter’s school like we’ve got friends, I’ve got mums that we all sort of just chat. So there is one of the mums who has recently just had a child as well, and so I have, so we sort of like you know you share tips, you talk about your experiences, what works, what doesn’t work.” (Parent, intervention centre).
We learnt that it was rare that parents would share advice without being prompted to do so. Instead, parents were most likely to discuss healthy behaviours when others asked others for advice: “With a parent if they’re struggling and they come to me for help and I've learnt it then I'll pass it on but I wouldn’t just go out and give it out in the street.” (Parent, intervention centre).
A small number of parents reported that they freely shared information if they thought it would provide benefit, as opposed to waiting to be asked for the advice: “I would share it definitely. I am somebody who would definitely share it. Especially with someone who I feel like would benefit from it. Or I could help their child or something I would definitely share it with them.” (Parent, intervention centre). This participant went on to specifically discuss the intervention and expressed that they would only share programme content with others who were attending the same centre: “Because you know, I am going to be honest with you, with the HENRY the only person I really discussed with HENRY was the other parents at the you know, the stay and play that didn’t go to it.” (Parent, intervention centre). Thus, the likelihood of parents sharing information outside of the centre was deemed to be low.
Some parents reported engaging with social media, predominantly to share existing posts. A small number of parents said they provided advice on social media or online forums: “I share on social media I'm part of a parenting support group on Facebook. So quite often we share little bits on there. If someone’s in some trouble we stick it up and there we all offer our advice.” (Parent, control centre).
Impact Of Contamination On Behaviour Change
There appeared to be key factors that influenced the likelihood that hearing healthy messages led to parents changing their behaviour. The frequency of hearing advice about a specific topic was a key factor, with both parents and staff suggesting that parents usually need to hear health advice repeatedly before they changed their behaviours: “You get these parents that come and it doesn’t sink in first time. A lot of these parents they are vulnerable…. I think it’s good that they repeat” (Staff, intervention centre).
A further factor that influenced the likelihood of the information changing behaviours was the source of the information. For example, parents appeared to talk highly of, and trust, the advice of professionals (e.g., children centre staff, and health visitors):
“Yes some of the health visitors again, our health visitors were really good. They would, you know, give you advice on what we were feeding our children. They would see things that you would give to them and say either oh that really good that you have given them that, or you should maybe wean them in this way. So yes it was definitely useful.” (Parent, control centre).
Strategies to mitigate risk of contamination in public health trials
Data from this nested qualitative study led to the production of a contamination risk framework (Fig. 1). This was produced through discussions with the research team, the steering committee and our parent advisory group, leading to the development of categories indicating the groups’ judgement of likelihood of contamination, and its potential impact on behaviour changes (related to trial outcomes). For example, staff working at multiple centres was reported frequently and appeared to have a large potential impact on contamination. Thus, it was categorised as a high risk behaviour. In contrast, parents sharing advice on social media was reported infrequently and appeared to have little potential for impacting behaviours. Thus it was categorised as a low risk behaviour.
We applied the contamination risk framework (Fig. 1) to develop strategies to both mitigate the risk of contamination in future trials through study design and develop strategies to monitor contamination during trial delivery. This will be applied to the future effectiveness trial, and can also be applied to other similar complex intervention trials delivered in community based, public health settings (Table 2). For example, to mitigate the intervention group staff sharing information with the control group staff, the importance of minimising contamination should be explained during training to discourage sharing of intervention information. In terms of monitoring contamination, sharing of information between intervention arms by the staff could be recorded.
Table 2
Key findings, contamination risk and strategies for mitigating risk in future RCTs
Source of contamination | Implication | Strategies to mitigate contamination | Strategies to monitor contamination |
High risk (high chance, high impact) |
Staff movement, as some staff worked across intervention and control children centres. | Some staff trained in intervention delivery shared HENRY messages at control sites through other programmes and when providing advice to parents. | • Ensure research setting is transparent about staff movement at the beginning of the study, so this can be considered during randomisation. • Ask staff not to share intervention content with control sites, and inform staff of the importance of reducing contamination so the importance of not sharing intervention content is understood • Deliver intervention outside of standard practice and as part of a research project. • Randomise at cluster level. | • Monitor staff movement at regular intervals |
Staff had knowledge of the programme prior to the study, and all staff were briefed on the study including the HENRY programme. HENRY content was available to parents through children’s centre staff sharing advice and role modelling behaviours. | Some staff in control centres knew about the HENRY programme. Some staff made personal changes to be healthier, as a result of being involved in the study. This impacted on the information, advice and guidance given to parents, as this was based on personal experience. | • Provide training to centre staff on RCTs and the importance of minimising contamination. • Record any prior knowledge of intervention amongst staff. • keep control staff blinded as much as possible to intervention content • Randomise at cluster level. | |
Staff meetings involved staff from control and intervention centres discussing best practice and programmes being run. | Some staff were aware that they should filter what was shared at these meetings, however found it challenging to do so. Some staff discussed sharing about intervention content to help staff at other centres. Staff routinely discussed programmes (including HENRY) at meetings. | • Encourage staff to not discuss the intervention at meetings, and to meet separately to discuss the programme with staff from the intervention arm only. • Inform staff of the importance of minimising contamination, so the importance of not sharing intervention content is understood. | • Report any sharing of information within meetings to research team. |
Medium- high risk (low chance/high impact) |
Parents shared experiences of the HENRY programme with each other | The majority of parents did not attend/ have contact with parents from multiple centres and sharing was limited to parents who attend the same groups. | • Ask participants to not share intervention content and materials until after the study is completed. | • Asking parents to disclose what contact they have with other study centres or parents who attend other centres. • Add ‘Contamination questions’ to test parental understanding of programme content and thus, identify contamination. |
Parents changed behaviour due to being recruited in study and aware of aim. | A few parents reported that they changed their behaviours once they had been recruited into the study as they knew that their weight was being monitored. | • Keep aim of study brief. • Promise intervention to control group once study is completed. | • Ask control participants if they have changed their behaviours due to being recruited into the study. |
Medium-low risk (high chance/low impact) |
Parents shared existing content on social media. | Parents shared advice that other people/organisations had already posted on social media. Parents were unlikely to share about HENRY and usually shared articles or asked/ answered specific questions from other parents. | • Parents could be asked not to share about the intervention on social media for duration of study. | • Record information shared on social media. |
Low risk (low chance/low impact) |
Some parents did not attend their local children’s centre and travelled further to attend one they preferred. | Parents did not have much contact with parents at other centres. If parents went to an intervention centre they may see HENRY displays/information. | • Do not encourage parents to attend other sites during study delivery. | • Monitor other centres that parents attend. |
Children's centers sharing parenting advice on social media | Children’s centres used social media to promote activities as part of routine practice. No parents reported knowledge of HENRY via social media or had shared about it. | • Recommendation that only intervention centres post about programme if social media is used. • Recommend that if social media is to be used, social media posts promote the programme but do not share intervention content. | • Monitor if intervention facilitators share intervention information on social media. |