[1] Kaiser Permanente Colorado, Inst Hlth Res, 2550 S Parker Rd,Suite 200, Aurora, CO 80014 USA
[2] Kaiser Permanente Northern Calif, Div Res, San Francisco, CA USA
[3] Kaiser Permanente San Francisco Med Ctr, Dept Gastroenterol, San Francisco, CA USA
[4] Univ Calif San Diego, Dept Internal Med, Div Gastroenterol, La Jolla, CA 92093 USA
[5] VA San Diego Healthcare Syst, 3350 La Jolla Village Dr,MC 11D, San Diego, CA 92160 USA