[1] Univ Calif San Diego, Div Infect Dis & Global Publ Hlth, San Diego, CA 92103 USA
[2] Rush Univ, Med Ctr, Sect Hepatol, Dept Internal Med, Chicago, IL 60612 USA
[3] Univ Penn, Perelman Sch Med, Philadelphia, PA 19104 USA
[4] Univ Bristol, Populat Hlth Sci, Bristol, Avon, England