1 University of North Carolina at Chapel Hill, Chapel Hill, NC. Electronic address: michael_kappelman@med.unc.edu.
2 Center for Clinical Epidemiology and Biostatistics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA.
3 Carelon Research, Wilmington, DE.
4 Research Department, Crohn's & Colitis Foundation, New York, NY.
5 Center for Clinical Epidemiology and Biostatistics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA; Department of Biostatistics, Epidemiology and Informatics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA.