[1] Vrije Univ Amsterdam, Dept Psychiat, NL-1075 BG Amsterdam, Netherlands
[2] Vrije Univ Amsterdam, Dept Social Sci Methodol, NL-1075 BG Amsterdam, Netherlands
[3] UCL, Inst Psychiat, Sect Epidemiol & Gen Practice, London WC1E 6BT, England
[4] UCL, Dept Epidemiol & Publ Hlth, London WC1E 6BT, England
[5] Royal Liverpool Univ Hosp, Dept Psychiat, Liverpool, Merseyside, England
[6] Oulu Univ Hosp, Unit Gen Practice, Oulu, Finland
[7] St James Hosp, Dept Psychiat, Jonathan Swift Clin, Dublin 8, Ireland
[8] Univ Munich, Dept Psychiat, D-8000 Munich, Germany
[9] Free Univ Berlin, Psychiat Klin & Poliklin, Berlin, Germany
[10] Hosp Clin Univ, Serv Psicosomat, Zaragoza, Spain
[11] Heilsugaeslustoo, Grundarfiroi, Iceland
[12] Univ Ghent, Res Grp Hlth & Behav, B-9000 Ghent, Belgium
[13] Univ Gothenburg, Sahlgrens Univ Hosp, Inst Clin Neurosci, Gothenburg, Sweden
[14] Osped Civile, Clin Psichiatr, Brescia, Italy