[1] Univ Penn, Perelman Sch Med, Dept Med, Div Gastroenterol, Philadelphia, PA USA
[2] Univ Penn, Ctr Clin Epidemiol & Biostat, Dept Biostat Epidemiol & Informat, Philadelphia, PA USA
[3] Univ Penn, Ctr Clin Epidemiol & Biostat, Perelman Sch Med, Philadelphia, PA USA
[4] CDCP, Div Viral Hepatitis, Atlanta, GA USA
[5] Univ Washington, Dept Med, Div Allergy & Infect Dis, Sch Med, Seattle, WA USA
[6] Univ Calif Los Angeles, David Geffen Sch Med, Dept Med, Div Infect Dis, Los Angeles, CA USA
[7] Univ Alabama Birmingham, Dept Med, Div Infect Dis, Birmingham, AL USA
[8] Univ N Carolina, Dept Med, Chapel Hill, NC USA
[9] Johns Hopkins Univ, Dept Med, Div Infect Dis, Baltimore, MD USA
[10] Case Western Reserve Univ, Dept Med, Cleveland Hts, OH USA
[11] Fenway Inst, Fenway Hlth, Boston, MA USA
[12] Harvard Med Sch, Beth Israel Deaconess Med Ctr, Dept Med, Boston, MA USA
[13] Univ Calif San Francisco, Dept Epidemiol & Biostat, San Francisco, CA USA
[14] Univ Penn, Perelman Sch Med, Dept Med, Div Infect Dis, Philadelphia, PA USA
[15] Ctr Clin Epidemiol & Biostat, Dept Biostat Epidemiol & Informat, 836 Blockley Hall, 423 Guardian Dr, Philadelphia, PA 19104 USA