1. University of Perugia; Department of Internal Medicine; Ospedale Santa Maria della Misericordia Località Sant'Andrea delle Fratte Perugia Italy 06126
2. Copenhagen Trial Unit, Centre for Clinical Intervention Research, Department 3344, Rigshospitalet, Copenhagen University Hospital; Cochrane Hepato-Biliary Group; Blegdamsvej 9 Copenhagen Denmark DK-2100
3. Gentofte University Hospital; Department of Internal Medicine; Niels Andersensvej 65 Hellerup Denmark 2900