The development and evaluation of a complex intervention to promote participant engagement with a public health programme

Public health programmes are aimed at promoting health and well-being, or preventing ill-health across communities and populations. The impact of public health programmes is often hindered by poor participant engagement. Yet, few interventions have been designed to address this, particularly those that demonstrate an effect. This thesis describes the development and evaluation of a participant engagement intervention aimed at promoting parent engagement with an obesity prevention programme (HENRY) delivered in UK children’s centres. Three studies were undertaken. The first, a focused ethnography study, explored the factors influencing parent engagement with HENRY. The second involved the development of a participant engagement intervention using the Behaviour Change Wheel approach. This intervention was tested in a cluster randomised controlled trial in work outside of the PhD. The third study within the PhD was a theory based process evaluation to provide explanation of the trial result. The results of the ethnography highlighted the role of implementation factors on parent engagement, including the ‘implementation climate’ which influenced how HENRY was perceived by parents. The importance of achieving local authority level buy-in was also revealed, along with its cascading effect on local implementation practices. The participant engagement intervention aimed to change behaviours across the children’s centre hierarchy to promote engagement with HENRY. This included local authority commissioners, children’s centre managers and staff. The trial of the intervention did not find a significant effect, but the process evaluation revealed challenges within the children’s centre context, such as financial constraints and centre closures which hindered implementation, engagement and uptake of the intervention, reducing potential impact. The findings of this thesis emphasise the importance of public health programmes receiving adequate engagement, infrastructural and organisational support. Without this, programme reach, sustainability and impact are threatened, risking waste of valuable public health resource.