A systematic review of adaptations and effectiveness of scaled-up nutrition interventions

Context Public health nutrition interventions shown to be effective under optimal research conditions need to be scaled up and implemented in real-world settings. Objectives The primary aim for this review was to assess the effectiveness of scaled-up public health nutrition interventions with proven efficacy, as examined in a randomized controlled trial. Secondary objectives were to: 1) determine if the effect size of scaled-up interventions were comparable to the prescale effect, and; 2) identify any adaptations made during the scale-up process. Data sources Six electronic databases were searched and field experts contacted. Study selection An intervention was considered scaled up if it was delivered on a larger scale than a preceding randomized controlled trial (prescale) in which a significant intervention effect (P <= 0.05) was reported on a measure of nutrition. Data extraction Two reviewers independently performed screening and data extraction. Effect size differences between prescale and scaled-up interventions were quantified. Adaptations to scale-up studies were coded according to the Adaptome model. Results Ten scaled-up nutrition interventions were identified. The effect size difference between prescale trials and scaled-up studies ranged from -32.2% to 222% (median, 50%). All studies made adaptations between prescale to scaled-up interventions. Conclusion The effects of nutrition interventions implemented at scale typically were half that achieved in prior efficacy trials. Identifying effective scale-up strategies and methods to support retainment of the original prescale effect size is urgently needed to inform public health policy. Systematic Review Registration PROSPERO registration no.CRD42020149267.

Automated summary

This review examines the effectiveness of scaled-up public health nutrition interventions and finds that the effects achieved at scale are typically only half of those achieved in prior efficacy trials. It highlights the need to identify effective scale-up strategies and methods to retain the original efficacy when implementing interventions at a larger scale, in order to inform public health policy.