[1] Univ Calif Los Angeles, David Geffen Sch Med, VA Greater Los Angeles Healthcare Syst, Los Angeles, CA 90073 USA
[2] VA Greater Los Angeles Hlth Care Syst, Div Gastroenterol Hepatol, Los Angeles, CA USA
[3] VA Greater Los Angeles Hlth Care Syst, Div Gen Internal Med Hlth Serv Res, Los Angeles, CA USA
[4] CURE Digest Dis Res, Los Angeles, CA USA
[5] Ctr Study Digest Healthcare Qual & Outcomes, Los Angeles, CA USA
[6] Univ Calif Los Angeles, Ctr Hlth Sci, Los Angeles, CA 90024 USA
[7] Univ Calif Los Angeles, Ctr Neurovisceral Sci & Womens Hlth, Los Angeles, CA USA