[1] Yale Univ, Sch Med, Sect Digest Dis, 333 Cedar St,1080 LMP, New Haven, CT USA
[2] Univ Calif Davis, Div Gastroenterol & Hepatol, Davis, CA 95616 USA
[3] Yale Sch Publ Hlth, Dept Biostat, New Haven, CT USA
[4] VA Pittsburgh Healthcare Syst, Pittsburgh, PA USA
[5] VA Connecticut Healthcare Syst, Dept Internal Med, West Haven, CT USA
[6] Yale Univ, Sch Med, Dept Internal Med, New Haven, CT 06510 USA
[7] Yale Sch Publ Hlth, Dept Hlth Policy & Management, New Haven, CT USA