1. Center for Clinical Epidemiology and Biostatistics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
2. Center for Pharmacoepidemiology Research and Training, Department of Biostatistics, Epidemiology, and Informatics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
3. Leonard Davis Institute of Health Economics, University of Pennsylvania, Philadelphia, Pennsylvania, USA
4. Ohio State University, Lima, Ohio
5. Eli Lilly and Company, Indianapolis, Indiana, USA
6. Division of Gastroenterology and Hepatology, Perelman School of Medicine, University of Pennsylvania , Philadelphia, Pennsylvania, USA