1. From the Department of Public Health (K.S.), University of Helsinki, Helsinki, Finland; Department of Medical Epidemiology and Biostatistics (P.K.E.M.) and Child and Adolescent Public Health Epidemiology Unit, Department of Public Health Sciences (M.N., P.T., F.R.), Karolinska Institute, Stockholm, Sweden; Department of Medical Sciences (J.S.), Uppsala University, Uppsala, Sweden; and MRC Social & Public Health Sciences Unit (G.D.B.), University of Glasgow, Glasgow, United Kingdom.