1. Center for Inflammatory Bowel Diseases (H.M.P., S.K.), Boston, Massachusetts 02115
2. Clinical Research Center Design and Analysis Core (P.D.M., H.J., R.F.-D.), Boston, Massachusetts 02115
3. Clinical and Translational Study Unit (D.D., N.Q.), Children's Hospital Boston, Boston, Massachusetts 02115
4. Center for Psychosocial Research in GI, Northwestern University Feinberg School of Medicine (R.C.L.), Chicago, Illinois 60611
5. Academic Medical Center (M.E.S.B., M.K.), 1105 AZ Amsterdam, The Netherlands
6. Divisions of Adolescent Medicine and Endocrinology, Hasbro Children's Hospital and Alpert Medical School of Brown University (C.M.G.), Providence, Rhode Island 02903