ReplaceIt: Lessons from a User-Centered Design Framework in Co-Creating an Alcohol Reduction App

Smartphone apps that target alcohol problems report mixed effectiveness data, which may be explained by a lack of evidence-based content and user-centred design (UCD). This paper presents the development of ReplaceIt, a smartphone application co-designed to reduce risky drinking using an evidence-based UCD framework. Initial steps included a systematic review of existing apps, interviews with end-users, and evidence-based intervention design by our multidisciplinary team, resulting in a prototype of the app. Next, the app's key components—goal setting, self-monitoring with feedback, and implementation intention strategies—were refined through co-design with end-users using a think-aloud study and iterative pilot testing. Refinement included the introduction of a module to enhance user interaction with implementation intentions, simplified instructions, and enhanced user engagement features. The resulting ReplaceIt app was then in an excellent position to undergo efficacy testing, with high usability scores and positive user reception suggesting strong potential for reducing risky drinking behaviours. Overall, the UCD framework proved essential in developing an app that aligns with user preferences and behaviours, ultimately enhancing its functionality and potential efficacy.