Development of Core Outcome Sets for Early intervention trials to Prevent Obesity in CHildren (COS-EPOCH)

Purpose: Core Outcome Sets (COS) are agreed minimum sets of outcomes recommended for measurement in studies for specific conditions or areas of health. COS development aims to improve the consistency, comparability and transparency of study findings and can help to reduce research waste. Few COS for public health interventions currently exist and there are no published COS that can be applied to obesity prevention interventions in children aged from birth to five years that include outcomes for multiple behaviour domains (e.g. food intake, movement, sleep). This study describes the development of a COS for randomised controlled trials (RCTs) evaluating lifestyle interventions for the prevention of obesity in 0-5 year olds (COS-EPOCH), and highlights some of the challenges faced in COS development.Methods: Overseen by an international Steering Group, the COS development process follows the Core Outcome Set-STAndards for Development recommendations. Development consists of three stages: (i) a scoping review of early childhood obesity prevention RCTs, identifying potential outcomes and measurement instruments; (ii) a modified Delphi study to determine core outcomes by relevant stakeholder group, followed by a consensus meeting to finalise core outcome recommendations; and, (iii) determination of recommended measurement instruments.Results/findings: Scoping review identified 170 relevant studies, with preliminary findings demonstrating there are a large number of outcomes currently collected in early childhood obesity prevention RCTs, and a broad range of outcome measurement instruments and methodologies employed. This high level of variation between studies makes evidence synthesis challenging, and further highlights the need for an agreed set of core outcomes. Delphi study development and recruitment is underway. Challenges in the development of the COS-EPOCH include the multiplicity of potential outcomes for inclusion, and the heterogeneity in completeness of study reporting in trial registries and the literature.Conclusions: The development of the COS-EPOCH will provide trialists with standardised sets of outcomes spanning the early childhood timeframe that takes into account this unique period of child development and incorporates multiple risk factors targeted in interventions. Effective dissemination of the COS-EPOCH will play a critical role in its future uptake