Impact of Alcohol Health Messages in a Real-world Online Retail Setting

The goal of this between-participants parallel randomized controlled trial conducted in the Systembolaget mobile application is to investigate the impact of exposure to health messages on cognition and behaviour. The primary study objective is to examine whether repeated exposure to rotating health warning messages in a mobile app where customers can purchase alcoholic beverages influences the number of purchased units of alcohol over the studied period. The secondary objectives are to examine whether repeated exposure to health warning messages in a mobile app influences the number of alcoholic and non-alcoholic products purchased over the studied period, knowledge of alcohol-related harms, alcohol-related risk perceptions, emotional response to the message, engagement with the messages, behavioural intentions and self-reported behaviour of the study participants. Users of the app providing informed consent for participation in the study will be assigned either to an experimental group, where they will be exposed to rotating messages describing health risks associated with alcohol designed in line with the existing Swedish regulation, or to a control group that will be exposed to messages reflecting existing industry practice. The intervention will last for ten weeks, during which the recruited participants\' data on product purchases in the app will be collected through in-app analytics. Both the number of alcoholic units and number of products purchased per session will be assessed and compared at the session level between the two groups. At the end of the intervention, participants will complete a short survey examining their knowledge, risk perceptions, emotional response, engagement with the messages, intentions and behaviour.