1 Department of Veterans Affairs San Diego Healthcare System, San Diego, California and, Division of Gastroenterology and, Moores Cancer Center, University of California San Diego, La Jolla, California.
2 Department of Gastroenterology, Kaiser Permanente Santa Clara Medical Center, Santa Clara, California and, Division of Research, Kaiser Permanente Northern California, Oakland, California.
3 Department of Medicine, Baylor College of Medicine, Houston, Texas.