1. Maastricht University (CAPHRI); Department of Family Medicine; P.debyeplein 1 Maastricht Zuid-Limburg Netherlands 6229 HA
2. IVO Addiction Research Institute; Rotterdam Netherlands
3. Maastricht University (CAPHRI); Department of Health Promotion; Maastricht Netherlands
4. Brown University; Department of Biostatistics, School of Public Health; Providence RI USA
5. Brown University; Department of Sociology; Providence USA
6. Brown University; Population Studies and Training Centre; Providence USA
7. Maastricht University; Department of Methodology and Statistics, Faculty of Health Medicine and Life Sciences (FHML); Debyeplein 1 Maastricht Netherlands 6200 MD
8. Maastricht University (CAPHRI); Department of Health Services Research; PO Box 616 6200 MD Maastricht Netherlands 6229 ER
9. Heinrich-Heine-University; Institute of General Practice, Addiction Research and Clinical Epidemiology, Medical Faculty; Düsseldorf Germany