[1] Washington Univ, Sch Med, Dept Surg, Div Publ Hlth Sci, St Louis, MO 63110 USA
[2] Washington Univ, Sch Med, Dept Med, Div Infect Dis, St Louis, MO 63110 USA
[3] Massachusetts Gen Hosp, Div Gastroenterol, Boston, MA 02114 USA
[4] Harvard Med Sch, Boston, MA 02115 USA
[5] Washington Univ, Sch Med, Dept Surg, St Louis, MO 63110 USA
[6] Washington Univ, Sch Med, Dept Med, Div Gastroenterol, St Louis, MO 63110 USA
[7] Harvard TH Chan Sch Publ Hlth, Dept Epidemiol, Boston, MA USA
[8] Amer Canc Soc, Behav & Epidemiol Res Grp, Atlanta, GA 30329 USA