1. Centre for Interdisciplinary Addiction Research, Department of Psychiatry, Medical Centre Hamburg-Eppendorf, Hamburg, Germany
2. Institute of Clinical Psychology and Psychotherapy & Center of Clinical Epidemiology and Longitudinal Studies, Technische Universität Dresden, Dresden, Germany
3. Center for Interdisciplinary Medicine Infectious Diseases, Muenster, Germany
4. Department of Gastroenterology and Hepatology, Muenster University Hospital, Muenster, Germany
5. Kompetenzzentrum Suchtmedizin, Infektiologie und Cannabis-Therapie, Hannover, Germany
6. MediZentrum Hamburg, Praxis für Suchtmedizin, Hamburg, Germany
7. Praxis MainFachArzt, Frankfurt am Main, Germany
8. LVR-Hospital Essen, Department of Addictive Behaviour and Addiction Medicine, Medical Faculty, University of Duisburg-Essen, Essen, Germany
9. Schwerpunktpraxis Concept, Munich, Germany
10. Center for HIV and Hepatogastroenterology, Düsseldorf, Germany
11. Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
12. Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada
13. Faculty of Medicine, Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
14. Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada
15. Gesundheit Nord, Bremen, Germany