V McAlister is responsible for correspondence. Search strategies were designed and run by Sarah Louse Klinkenberg, The Cochrane Hepato‐Biliary Group Trials Search Co‐ordinator, and they were approved by all authors. E Davenport searched the abstracts of Digestive Disease Week. V McAlister and E Renouf independently reviewed the search results for potential studies to be included. E Davenport and E Renouf assessed the trials and extracted data. Differences were resolved by V McAlister after discussion. V McAlister performed the analyses on RevMan 4.2. E Davenport and E Renouf reviewed the analyses. V McAlister wrote the first draft of the report . Revisions were suggested by E Davenport and E Renouf. All authors approved of the final review before submission.