Assessing the effectiveness of HIV/STI risk communication displays among Melbourne Sexual Health Centre attendees: a cross-sectional, observational and vignette-based study

Introduction: Increasing rates of sexually transmitted infections (STIs) over the past decade underscore the need for early testing and treatment. Communicating HIV/STI risk effectively can promote individuals' intention to test, which is critical for the prevention and control of HIV/STIs. We aimed to determine which visual displays of risk would be the most likely to increase testing or use of prevention strategies. Methods: A vignette-based cross-sectional survey was conducted with 662 clients (a median age of 30 years (IQR: 25-36), 418 male, 203 female, 41 other genders) at a sexual health clinic in Melbourne, Australia, between February and June 2023. Participants viewed five distinct hypothetical formats, presented in a randomised order, designed to display the same level of high risk for HIV/STIs: icon array, colour-coded risk metre, colour-coded risk bar, detailed text report and guideline recommendation. They reported their perceived risk, concern and intent to test for each risk display. Associations between the format of the risk display and the intention to test for HIV/STI were analysed using logistic regression. Results: About 378 (57%) of participants expressed that the risk metre was the easiest to understand. The risk metre (adjusted OR (AOR)=2.44, 95% CI=1.49 to 4.01) and risk bar (AOR=2.08, CI=1.33 to 3.27) showed the greatest likelihood of testing compared with the detailed text format. The icon array was less impactful (AOR=0.73, CI=0.57 to 0.94). The risk metre also elicited the most concern but was the most preferred and understood. High-risk perception and concern levels were strongly associated with their intention to have an HIV/STI test. Conclusions: Displaying risk differently affects an individual's perceived risk of an HIV/STI and influences their intention to test.