Table 3 Summary of design recommendations

How can the reach of evidence-based apps be improved?

Develop smoking cessation and alcohol reduction apps that are on a par with other commercially available apps in terms of aesthetics and usability, perhaps through collaboration with interaction design experts.

Researchers and practitioners may consider initiating collaborations with developers of popular apps and/or apps from well-known brands to leverage their existing ‘social proof’.

Use simple and straightforward titles that include key words (e.g. “quit smoking” or “reduce your drinking”).

How can engagement be improved?

Use persuasive design elements (e.g. guidance, tunnelling, normative influence) to modify users’ beliefs about how to quit smoking or reduce their drinking.

Use machine-learning techniques to explore how to meaningfully tailor content according to individual differences (e.g. feedback, rewards).

Develop response-sensitive notifications that tail off or adjust timings if the user stops reacting in order to prevent habituation or annoyance.

Consider the online and offline social preferences of the target population. For example, it might be more fruitful to focus on action planning and/or behaviour substitution rather than in-the-moment support for smokers and drinkers.