1 Brigham and Women's Hospital and Harvard Medical School, Center for Crohn's and Colitis, Boston, Massachusetts; Center for Clinical Epidemiology, Odense University Hospital and Research Unit of Clinical Epidemiology and Department of Clinical Research, University of Southern Denmark, Odense, Denmark. Electronic address: sfriedman1@bwh.harvard.edu.
2 Brigham and Women's Hospital and Harvard Medical School, Center for Crohn's and Colitis, Boston, Massachusetts; Center for Clinical Epidemiology, Odense University Hospital and Research Unit of Clinical Epidemiology and Department of Clinical Research, University of Southern Denmark, Odense, Denmark.