[1] Univ N Carolina, UNC Liver Ctr, Div Gastroenterol & Hepatol, 8004 Burnett Womack,CB 7584, Chapel Hill, NC 27599 USA
[2] Univ N Carolina, Gillings Sch Global Publ Hlth, Dept Epidemiol, Chapel Hill, NC 27515 USA
[3] Carolinas Healthcare Syst, Ctr Outcomes Res & Evaluat, Charlotte, NC USA
[4] Univ Pittsburgh, Med Ctr, Ctr Liver Dis, Pittsburgh, PA USA