1. Department of Visceral and Transplantation Surgery, University Hospital Zurich, Zurich, Switzerland
2. Division of Gastroenterology and Hepatology, University Hospital Zurich, Zurich, Switzerland
3. The Horten Centre, University Hospital Zurich, Zurich, Switzerland
4. Division of Epidemiology and Biostatistics, Department of Social and Preventive Medicine, University of Bern, Switzerland