1. The Cochrane Hepato-Biliary Group, Copenhagen Trial Unit, Center for Clinical Intervention Research, Department 7812, Rigshospitalet; Copenhagen University Hospital; Copenhagen Denmark
2. Department of Internal Medicine; Ospedale A. Manzoni; Lecco Italy
3. Second Division of Gastroenterology, IRCCS Fondazione Cà Granda Ospedale Maggiore Policlinico; Università degli Studi di Milano; Milan Italy
4. Department of Biomedical and Clinical Sciences; “L. Sacco,” Università degli Studi di Milano; Milan Italy
5. Department of Clinical Epidemiology and Biostatistics; McMaster University; Hamilton Ontario Canada