[1] Univ Maryland, Med Ctr, Div Gastroenterol & Hepatol, Baltimore, MD 21201 USA
[2] Univ Maryland, Sch Pharm, Dept Pharmaceut Hlth Serv Res, Baltimore, MD 21201 USA
[3] Univ Maryland, Sch Med, Dept Epidemiol & Prevent Med, Baltimore, MD 21201 USA
[4] Univ Maryland, Sch Med, Dept Med, Div Gastroenterol & Hepatol, Baltimore, MD 21201 USA
[5] Maryland Hlth Care Syst, Vet Affairs, Baltimore, MD USA