"How do online and offline sampling compare in a multinational study of drug use and nightlife behaviour?"

Methods: Online participants who attended at least six nightlife events in the past 12 months were recruited using social media advertising (May-November 2017). Offline participants were recruited at nightclubs and festivals using a random intercept method (May-November 2017). Samples were compared with respect to age, gender, past year use of alcohol, cannabis, cocaine, ecstasy/MDMA and amphetamines, and past year attendance at nightclubs, licensed festivals, illegal festivals, pubs and house-parties.

Background: Online sampling is widely used to recruit hard to reach samples such as drug users at nightlife events. We conducted the first study comparing differences in demographics, drug use and nightlife behaviour between an online sample of young adults engaging with the European nightlife scene, and an offline sample recruited at nightclubs and festivals in Europe.