[1] Fac Med Toulouse, INSERM, Dept Epidemiol, Fac Med,U558, F-31073 Toulouse, France
[2] Pasteur Inst Lille, INSERM, U508, Lille, France
[3] Fac Med, Dept Epidemiol & Publ Hlth, Strasbourg, France
[4] Hop Paul Brousse, INSERM, U258, Villejuif, France