1. Ulyanovsk Regional Clinical Hospital; Department of Gastroenterology; International 3 Ulyanovsk Russian Federation 432063
2. Center for Evidence-Based Medicine; 'Sechenov' First Moscow State Medical University; Pogodinskaya 1 Moscow Russian Federation 119991
3. Copenhagen Trial Unit, Centre for Clinical Intervention Research, Department 7812, Rigshospitalet, Copenhagen University Hospital; Cochrane Hepato-Biliary Group; Blegdamsvej 9 Copenhagen Sjaelland Denmark DK-2100
4. Kazan Federal University; 18 Kremlyovskaya Kazan Russian Federation 420008
5. Università degli Studi di Milano; Dipartimento di Scienze Biomediche e Cliniche "L. Sacco"; via GB Grassi 74 Milan Italy 20157