Abstract
BACKGROUND: Child health and wellbeing is influenced by multiple factors, all of which can impact on early childhood development. Adverse early life experiences can have lasting effects across the life course, sustaining inequalities and resulting in negative consequences for the health and wellbeing of individuals and society. The potential to influence future outcomes via early intervention is widely accepted; there are numerous policy initiatives, programmes and interventions clustered around the early years theme, resulting in a broad and disparate evidence base. Existing reviews have addressed the effectiveness of early years interventions, yet there is a knowledge gap regarding the mechanisms underlying why interventions work in given contexts. METHODS/DESIGN: This realist review seeks to address the question 'what works, for whom and in what circumstances?' in terms of early years interventions to improve child health and wellbeing. The review will be conducted following Pawson's five-stage iterative realist methodology: (1) clarify scope, (2) search for evidence, (3) appraise primary studies and extract data, (4) synthesise evidence and draw conclusions and (5) disseminate findings. The reviewers will work with stakeholders in the early stages to refine the focus of the review, create a review framework and build programme theory. Searches for primary evidence will be conducted iteratively. Data will be extracted and tested against the programme theory. A review collaboration group will oversee the review process. DISCUSSION: The review will demonstrate how early years interventions do or do not work in different contexts and with what outcomes and effects. Review findings will be written up following the RAMESES guidelines and will be disseminated via a report, presentations and peer-reviewed publications. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42015017832.