[1] Massachusetts Gen Hosp, Crohns & Colitis Ctr, Gastrointestinal Unit, Boston, MA 02114 USA
[2] Harvard Univ, Sch Med, Boston, MA USA
[3] Partners Hlth Care Syst, Informat, Boston, MA USA
[4] Harvard Univ, Sch Publ Hlth, Dept Biostat, Boston, MA 02115 USA
[5] I2b2 Natl Ctr Biomed Comp, Boston, MA USA
[6] Brigham & Womens Hosp, Div Rheumatol Immunol & Allergy, Boston, MA 02115 USA