[1] Univ Amsterdam, Acad Med Ctr, Dept Internal Med, NL-1100 DD Amsterdam, Netherlands
[2] Univ Dusseldorf, Div Gastroenterol Hepatol & Infect Dis, D-4000 Dusseldorf, Germany
[3] Univ Amsterdam, Acad Med Ctr, Dept Clin Epidemiol & Biostat, NL-1100 DD Amsterdam, Netherlands