1. Division of Gastroenterology and Hepatology, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
2. Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania, Philadelphia, Pennsylvania, USA
3. Duke Clinical Research Institute, Duke University, Durham North Carolina, USA
4. Division of Gastroenterology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
5. Department of Biostatistics and Epidemiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
6. Abramson Cancer Center, University of Pennsylvania, Philadelphia, Pennsylvania, USA
7. Division of Clinical Immunology and Rheumatology, University of Alabama at Birmingham, Birmingham, Alabama, USA
8. Department of Epidemiology, University of Alabama at Birmingham, Birmingham, Alabama, USA