Designing engaging online behaviour change interventions : a proposed model of user engagement

To date, the majority of online health behaviour interventions have been guided by theories of behaviour change. These theories provide valuable information about how to apply intervention strategies to produce changes in determinants of behaviour. However, they provide little guidance on how to engage participants in online interventions. This is a significant limitation, given the known impact that participant engagement has on intervention efficacy, and the consistent reporting of difficulties relating to participant engagement in online interventions. To encourage user engagement, and ultimately improve intervention efficacy, a greater focus on the determinants of user engagement is needed. This paper discusses the need for integrated theory approaches to guide the development and evaluation of intervention strategies targeting behavioural determinants of health behaviour change, as well as strategies targeting the determinants of user engagement in a web-based context. To promote the consideration of these determinants in a theoretical and evidence-based manner, a conceptual model of engagement is proposed that can be operationalised alongside behaviour change theory to guide future intervention development.