1. Department of Epidemiology; Lazio Regional Health Service; Rome Italy
2. Mental Health and Substance Abuse; World Health Organization; Geneva Switzerland
3. National Drug and Alcohol Research Centre; University of New South Wales; Sydney Australia
4. School of Social and Community Medicine; University of Bristol; Bristol UK
5. The School of Medicine; University of Melbourne; Melbourne Vic Australia
6. Drug Evaluation Unit; WHO Collaborating Centre in Evidence-Based Research Synthesis and Guideline Development; Emilia Romagna Health and Social Care Agency; Bologna Italy
7. Departments of Clinical Epidemiology & Biostatistics and of Medicine; McMaster University Health Sciences Centre; Hamilton Canada