1. Department of Biostatistics, MD Anderson Cancer Center, Houston, Texas, USA;
2. Department of Internal Medicine, University of Kentucky College of Medicine, Lexington, Kentucky, USA;
3. Division of Gastroenterology, Hepatology and Nutrition, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA;
4. Division of Gastroenterology, Hepatology and Nutrition, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA;
5. Digestive and Liver Disorders, Department of Medicine, Indiana University, Indianapolis, Indiana, USA;
6. Department of Surgery, Baylor College of Medicine, Houston, Texas, USA;
7. Division of Gastroenterology, Hepatology and Nutrition, University of Florida, Gainesville, Florida, USA;
8. Division of Digestive and Livers Diseases, Cedars-Sinai Medical Center, Los Angeles, California, USA;
9. Division of Gastroenterology and Hepatology, Department of Medicine, Stanford University, Stanford, California, USA;
10. Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota, USA;
11. Division of Digestive Diseases and Nutrition, NIDDK, NIH, Bethesda, Maryland, USA;
12. Division of Research, Kaiser Permanente Northern California, Oakland, California, USA.