1 Division of Digestive Diseases, Division of General Internal Medicine and Health Services Research, David Geffen School of Medicine at University of California, Los Angeles, California.
2 Greater Los Angeles Veterans Affairs Healthcare System, Division of General Internal Medicine and Health Services Research, David Geffen School of Medicine at University of California, Los Angeles, California.
3 Division of General Internal Medicine and Health Services Research, David Geffen School of Medicine at University of California, Los Angeles, California.