1. Division of Gastroenterology and Hepatology, University of Michigan, Ann Arbor, Michigan, USA;
2. Vatche and Tamar Manoukian Division of Digestive Diseases, Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California, USA;
3. UCLA Kaiser Permanente Center for Health Equity, UCLA Jonsson Comprehensive Cancer Center, Los Angeles, California, USA;
4. Department of Medicine, VA Greater Los Angeles Healthcare System, Los Angeles, California, USA;
5. Emory School of Medicine, Atlanta, Georgia, USA;
6. Gastroenterology Section, VA Ann Arbor Healthcare System, Ann Arbor, Michigan, USA.