[1] Univ Autonoma Barcelona, Hosp Mar, Hlth Serv Res Unit, IMIM, E-08003 Barcelona, Spain
[2] Univ Manchester, Natl Drug Evidence Ctr, Manchester, Lancs, England
[3] Univ Glasgow, Ctr Drug Misuse Res, Glasgow, Lanark, Scotland
[4] CIBER Epidemiol & Salud Publ CIBERESP, Sao Paulo, Brazil