A scoping review of studies applying the Nuffield's 'intervention ladder' framework to assess the acceptability of diet and physical activity interventions.

backgroundThe Nuffield's Intervention Ladder (NIL) framework casts public acceptability of health interventions based on their level of intrusiveness- how much they restrict personal autonomy and freedom of choice. This scoping review explores the application of the NIL framework in assessing public acceptability of diet and physical activity interventions, identifying key trends, gaps, and alignment with the framework's conceptual underpinnings.

methodsWe searched six databases (PubMed, Scopus, Medline, Embase, Science Direct, and Web of Science) and included 15 eligible studies. Data were charted and synthesized thematically and narratively.

resultsThe NIL framework was applied across different study designs, primarily post hoc, to categorize interventions based on their intrusiveness. Consistent with the framework, less intrusive interventions (information provision, enabling choice) were widely accepted. Moderately intrusive interventions (changing defaults, incentives, and disincentives) received mixed public acceptance, whereas highly intrusive interventions (restrict and eliminate choice) generally garnered lower public acceptability. Highly intrusive interventions were publicly acceptable when they are directed at children, or at industries. Across all intervention types, demographic and behavioural factors significantly influenced public acceptance.

conclusionThe NIL framework offers useful insights into how intrusiveness affects public acceptability of interventions. However, the review highlights that various factors influence acceptability in ways that extend the framework's initial propositions.