[1] Univ Penn, Perelman Sch Med, Dept Med, Philadelphia, PA USA
[2] Univ Penn, Perelman Sch Med, Div Gastroenterol & Hepatol, Philadelphia, PA USA
[3] Corporal Michael J Crescenz VA Med Ctr, Dept Med, Philadelphia, PA USA
[4] VA Connecticut Healthcare Syst, West Haven, CT USA
[5] Univ Penn, Ctr Clin Epidemiol & Biostat, Perelman Sch Med, Dept Biostat Epidemiol & Informat, Philadelphia, PA USA
[6] Univ Penn, Leonard David Inst Hlth Econ, Perelman Sch Med, Philadelphia, PA USA
[7] 3400 Civ Ctr Blvd,4th Floor,South Pavilion, Philadelphia, PA 19104 USA