Lost in Translation: Transforming Behaviour Change Techniques into Engaging Digital Content and Design for the StopApp.

Frameworks to support the application of behaviour change theory to the choice of behaviour change techniques (BCTs) in designing digital behaviour change interventions (DBCIs) are becoming well established, and have been employed by the authors in the development of StopApp. However, guidance on the next stage-effective operationalisation (translation) of these BCTs to a digital context, including the precise delivery and design of "behavioural intervention technology" (BIT) elements, is still in its infancy. This is despite growing recognition of the need to optimise engagement and usability, alongside a theoretical basis, for intervention effectiveness. The aim of this study was to explore methods to translate BCTs into digital content in an accurate and systematic manner. We describe the process of using co-creation (user-led) rather than expert-driven methods in the development of user-facing features and design in StopApp, including the iterative "bottom-up" and "top-down" processes necessary for accurate BCT translation. We found a small disparity between the intended and actual BCT content, reflecting the difficulties of translating BCTs into digital intervention content and the need for better guidance and methodical approaches to enhance this under-researched process. The involvement of our Patient and Public Involvement (PPI) group throughout these processes is described.