1. Division of Gastroenterology Perelman School of Medicine University of Pennsylvania Philadelphia PA USA
2. Leonard David Institute of Health Economics University of Pennsylvania Philadelphia PA USA
3. Center for Clinical Epidemiology and Biostatistics Department of Biostatistics, Epidemiology & Informatics Perelman School of Medicine University of Pennsylvania Philadelphia PA USA
4. Department of Medicine Corporal Michael J. Crescenz VA Medical Center Philadelphia PA USA
5. Division of Digestive Diseases Yale University School of Medicine New Haven CT USA
6. VA Connecticut Healthcare System West Haven CT USA
7. Division of Digestive Health and Liver Diseases Department of Medicine University of Miami Miller School of Medicine Miami FL USA