Recreational drug use in the Oslo nightlife setting: study protocol for a cross-sectional time series using biological markers, self-reported and qualitative data

INTRODUCTION Recreational drug use in the nightlife setting carries the risk of many negative consequences, such as violence, injuries, aberrant driving and sexual risk-taking. The aim of this study is to investigate recreational drug use and user characteristics among people visiting licensed premises, for example, nightclubs and bars, by using self-reports and biological markers. Staff of licensed premises will be asked to report drug use observations. Further, by using qualitative data, we will examine the motives, consequences and culture associated with recreational drug use. An additional aim is to compare self-reported drug use with oral fluid test (OFT) results in order to validate the different measurement methods in this context. METHODS AND ANALYSES Data collection will be conducted among patrons (n=1000) outside licensed premises. On consent, patrons will be asked to anonymously complete a questionnaire, a breath alcohol concentration test and an OFT. Patrons who report use of recreational drugs in the previous 12 months will be asked to leave their contact information for a subsequent qualitative in-depth interview (n=30-40). Staff from licensed premises (n=500) will be invited during Responsible Beverage Service Training to participate in an anonymous survey. Survey data will be analysed by univariate and multivariate statistical methods and the oral fluids will be analysed for a large number of drugs using biochemical methods. Cohen's κ will be used as a measure of agreement between self-reported drug use and OFT. In-depth interviews will be coded in HyperRESEARCH and analysed using an inductive approach. Data collection will be repeated on a biannual basis until at least 2020, allowing for examination of trends in recreational drug use. ETHICS AND DISSEMINATION This study has been approved by the Regional Committee for Medical and Health Research Ethics. Results will be disseminated in research journals, conferences and the media.