1. University of Sherbrooke; Department of Community Health Sciences, Addiction Research Study Program; Longueuil Québec Canada
2. Charles-LeMoyne Hospital Research Centre; Longueuil Québec Canada
3. Institut national de santé publique du Québec; 190 Crémazie E Montréal Québec Canada
4. McGill University; Department of Epidemiology and Biostatistics; Montréal Québec Canada