Community health and well-being workers (CHWWs) for preventive healthcare services uptake in the UK: a cluster-randomised controlled trial protocol

Introduction Recognised within the National Health Service (NHS) 10-year plan as an innovative workforce solution to enable the left shift care towards integrated, neighbourhood models, community health and well-being workers (CHWWs) are rapidly expanding across England. Inspired by Brazil’s Family Health Strategy, the model has scaled from an initial pilot in Westminster to over 28 localities. However, despite this national expansion, robust empirical evidence of its impact remains limited. This protocol describes a pragmatic cluster randomised controlled trial in Westminster designed to provide definitive evidence on whether embedding CHWWs within local communities effectively improves the uptake of preventive healthcare services. Methods and analysis A pragmatic, parallel-group, superiority cluster-randomised controlled trial is being conducted using routinely collected electronic health records. 60 geographically defined ‘village’ clusters (approximately 120 households in each cluster, 7200 households in total) located in socioeconomically deprived areas of Westminster, London, were randomised (1:2 allocation ratio) to either the intervention or control group. The intervention involves locally recruited CHWWs conducting comprehensive, proactive monthly household visits to promote preventive care and address social determinants of health between January 2024 and December 2025. The control group receives usual care. The primary outcome is the Composite Referral Completion Indicator (CRCI), defined as the household-level rate of completed eligible preventive healthcare services per person-year (including immunisations, cancer screenings and NHS Health Checks). Secondary outcomes include individual preventive service uptake and healthcare utilisation metrics (eg, general practice and accident and emergency attendances). Outcomes will be extracted from the Whole Systems Integrated Care (WSIC) database. Primary analysis will follow the intention-to-treat principle using generalised linear mixed models, supplemented by hierarchical targeted maximum likelihood estimation for absolute effects. Ethics and dissemination The study relies on de-identified, routinely collected data to evaluate a new routine primary care service. Individual informed consent was waived because the use of retrospective routinely collected data for analysis fell under the existing global ethics agreement for the WSIC database (REC reference: REC18/WM/0323/IRAS252449). Nevertheless, the study was reviewed and approved by the Health Research Authority (HRA 23/HRA/4972; 20 December 2023). Results will be disseminated through peer-reviewed academic publications, conference presentations and plain-language summaries shared with the local community. Trial registration number NCT06144580.