[1] Brigham & Womens Hosp, Dept Med, Div Pharmacoepidemiol & Pharmacoecon, 75 Francis St, Boston, MA 02115 USA
[2] Harvard Med Sch, Boston, MA 02115 USA
[3] Sorbonne Univ, Hop St Antoine, AP HP,Dept Gastroenterol, INSERM,Inst Pierre Louis Epidemiol & Sante Publ, Paris, France