1. Department of Gastroenterology; Helsinki University Central Hospital; Helsinki Finland
2. Gastroenterology and Endoscopy Unit; Department of Pathophysiology and Transplantation; Fondazione IRCCS Cà Granda Ospedale Maggiore Policlinico; Università degli Studi di Milano; Milan Italy
3. Department of Public Health; Hjelt Institute; University of Helsinki; Helsinki Finland
4. Institute of Clinical Medicine; University of Helsinki; Helsinki Finland