[1] Johns Hopkins Univ, Sch Med, Dept Med, Harvey M & Lyn P Meyerhoff Inflammatory Bowel Dis, Baltimore, MD 21205 USA
[2] Johns Hopkins Univ, Bloomberg Sch Publ Hlth, Ctr Hlth Dispar Solut, Baltimore, MD 21205 USA
[3] Johns Hopkins Med Inst, Dept Surg, Baltimore, MD 21205 USA
[4] Johns Hopkins Univ, Bloomberg Sch Publ Hlth, Dept Epidemiol, Baltimore, MD USA