Process and outcome evaluation of a social norms approach intervention on alcohol use among Flemish university students: a quasi-experimental study.

Background: Alcohol consumption is prevalent among students, with a common tendency to overestimate peers' alcohol use, contributing to increased consumption. This misperception is evident among Flemish students. This study aimed to develop and assess a Social Norms Approach (SNA) intervention targeting Flemish students to correct misperceptions and subsequently reduce alcohol use.

Methods: The 'Alcoholfacts' social media campaign was implemented using a quasi-experimental design from November 2022 to March 2023. A process evaluation followed Medical Research Council guidance, and intervention effects were evaluated using baseline and post-intervention surveys. Multiple linear regression with a Difference-in-Difference approach was performed for outcome assessment, using an intention-to-treat approach.

Results: The process evaluation showed that 36.3% of the intervention group had seen the campaign and that most of the exposed students found the campaign credible (73.3%). However, 54.8% of the exposed students did not find the campaign appealing. Results of the outcome assessment indicated that students of the intervention group at endline estimated students' alcohol consumption significantly lower (bootstrapped p = 0.013; B = -1.93, bootstrapped CI = -3.620 to -0.565) compared to students of the control group. However, no significant intervention effect on student's alcohol consumption was found (bootstrapped p = 0.741; B = -0.32, bootstrapped CI = -2.101 to 1.534).

Conclusions: The study supports the efficacy of an SNA campaign in correcting misperceptions but did not yield an immediate reduction in alcohol consumption. Future research should involve the target group in campaign material development to enhance attractiveness and impact.