1. Division of Gastroenterology and Hepatology, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109, USA
2. Institute for Healthcare Policy and Innovation, University of Michigan, Ann Arbor, MI 48109, USA
3. Michigan Integrated Center for Health Analytics and Medical Prediction, University of Michigan, Ann Arbor, MI 48109, USA
4. Department of Statistics, University of Michigan, Ann Arbor, MI 48109, USA
5. VA HSR&D Center for Clinical Management Research, Ann Arbor, MI 48105, USA