All authors are kindly requested to add the following text under Acknowledgements:

"Cochrane Hepato-Biliary Review Group (CHBG) funding acknowledgement: the Danish State is the largest single funder of the CHBG through its investment in the Copenhagen Trial Unit, Centre for Clinical Intervention Research, the Capital Region, Rigshospitalet, Copenhagen, Denmark. 
Disclaimer: the views and opinions expressed in this review are those of the authors and do not necessarily reflect those of the Danish State or the Copenhagen Trial Unit."