[1] CHU Vaudois, Dept Gastroenterol & Hepatol, Rue Bugnon 44, CH-1011 Lausanne, Switzerland
[2] Univ Lausanne, Rue Bugnon 44, CH-1011 Lausanne, Switzerland
[3] Univ Bern, Inst Social & Prevent Med, Mittelstr 43, CH-3012 Bern, Switzerland
[4] Univ Utah, Dept Internal Med, Div Gastroenterol & Hepatol, 50 North Med Dr,SOM 4R118, Salt Lake City, UT 84132 USA