Carrie Wong

Issue Addressed Obesity in children is one of the most significant public health issues globally. Given the high prevalence of overweight and obesity in children, there is a need to identify effective obesity prevention efforts that can be delivered at scale to improve child health. We aimed to (i) identify obesity prevention interventions targeted at children aged 0–2 that have been scaled‐up, and their relative efficacy compared to their pre‐scale trial, (ii) describe adaptations made, and the extent to which factors related to scalability have been reported. Methods We conducted a rapid review of pre‐scale randomised controlled trials targeting nutrition, physical activity and obesity prevention in infants, and calculated the relative effect size for relevant outcomes in the corresponding scaled up trial. We documented adaptations made to the pre‐scale trial for scale up, and explored how different components of scalability had been reported according to the Intervention Scalability Assessment Tool. Results Of the 14 identified pre‐scale trials, only one formal evaluation of the scale‐up trial was identified. For body mass index, <10% of the effect was retained, however for nutrition and behavioural outcomes, the proportion of effect retained varied from −11.1% to 144%. Significant adaptations to modality were made in the scaled up trial primarily to reduce cost and increase reach of the intervention. Reporting of scalability components varied across the 14 trials, with only one trial reporting information for all assessed components. Conclusions The majority of effective interventions targeting obesity prevention in infants have not been evaluated in a scaled up form. The magnitude of effect retained for the single trial that was scaled up was variable. In general, reporting of components of scalability was sub‐optimal. So What? The findings suggest that there is substantial need for the development and rigorous evaluation of obesity prevention interventions in children aged 0–2 which are amenable for scale.