Review for 10.1186/s12876-020-01226-x (2020)

Reviewer ’s report  
 
Title: Endoscopic stent placement above the sphincter of Oddi for biliary strictures after living 
donor liver transplantation.  
 
Version: 2 Date: 06 Jan 2020  
 
Reviewer: Deborah J Verran  
 
Reviewer's report:  
 
This is a retrospective analysis of a case series of adults requiring endoscopic management of 
biliary strictures following live donor liver transplantation. It appears that with the passage of 
time the end oscopic management of these biliary strictures in this particular institution has 
evolved such that ERCP and placement of an internal stent has become a first line approach 
(although it is not clear when exactly this happened ) and that you are now reporti ng on this 
experience along with discussing what are the implications for clinical practice moving forward.  
 
The manuscript does not read as well as it could partly because there is a lack of attention paid to 
providing the current background knowledge for  both the rationale as well as the clinical 
outcomes for the ever increasing use of the internal biliary stent (IS) in the management of 
biliary strictures in the adult live donor liver transplant population (including in the 
Introduction). Two publication s in the last 5 years have summarised what is known about the use 
of IS (particularly in Japan) and how this practice appears to be on the increase but at this stage 
there is limited data on the outcomes (hence why there is no consensus as yet). This also ties into 
the Discussion section of the manuscript where the information from these additional 
manuscripts needs to be used to enhance the discussion.  
 
The review article from Shin M, Joh, J -W, titled Advances in endoscopic management of biliary 
complicati ons in living donor liver transplantation. Comprehensive review of the literature. 
World J of gastroenterology 2016, 22 (27) 6173 -6191, is an excellent summary of the evolution 
in management of biliary strictures in this particular patient population.  
 
The results section needs to focus on the data. Adding in the information from one case seems 
superfluous. A relevant image of a biliary stricture being managed however seems useful. There 
are too many Tables. Table 1 seems superfluous in light of the data pr ovided in Table 2. I am not 
sure of the utility of the Kaplan Meier outcome curves for stenting, plus in Table 3 the data needs 
to be separated out for the rates of stent occlusion versus stent migration so that they are clearer 
to the reader (and the stat istical analysis repeated). You also need to add in the data on the 
incidence of bile duct stones with either IS or ES into table 3 as well (because this is mentioned 
in the discussion, although no mention is made wrt how your experience with managing ston es in 
this setting compares to the other reports from Japanese centres). NB although you have not 
reached statistical significance for the rates of the different complications between the internal 
and external stents this does not mean that there are not t rends. You are limited by the small size 
of your patient cohort, which you have mentioned in the final paragraph of the discussion. 
Although you mention that there is the need for a prospective randomised controlled trial you 
have not mentioned what are th e current barriers to such a trial being undertaken (of which there 
must be at least several).  
 
It would also be useful to also expand on what contributes to the technical success as well as the 
failure of the endoscopic placement of internal biliary sten ts in your experience compared to all 
of the recent series in published literature. You have alluded to the fact that you did not use 
multiple stents as others have reported but have provided little actual info on how your practice 
currently varies from ot her units in Japan.  
 
The mention of metallic stents including for malignant biliary obstruction does not add value to 
the discussion and in fact seems not of much relevance. Similarly referencing publications on the 
use of metal stents for malignant bilia ry obstruction is not useful for this type of manuscript. The 
publication from Tsujino et al, titled Endoscopic management of biliary strictures after living 
donor liver transplantation. Clin J Gastroenterol 2017, 10: 297 -311, covers this topic extremely 
well and is a far more comprehensive account of what is currently known.  
 
Are the methods appropriate and well described?  
If not, please speci fy what is required in your comments to the authors.  
 
Yes 
 
Does the work include the necessary controls?  
If not, please specify which controls are required in your comments to the authors.  
 
Unable to assess  
 
Are the conclusions drawn adequate ly supported by the data shown?  
If not, please explain in your comments to the authors.  
 
No 
 
Are you able to assess any statistics in the manus cript or would you recommend an 
additional statistical review?  
If an additional s tatistical review is recommended, please speci fy what aspects require further 
assessment in your comments to the editors.  
 
I recommend additional statistical review  
 
Quality of written English  
Please indicate the quality of language in the manuscript:  
 
Needs some language corrections before being published  
 
Declaration of competing interests  
Please complete a declaration of competing interests, considering the following questions:  
 
1.  Have you in the past five years received reimbursements, fees, funding, or sal ary 
from an organisation that may in any way gain or lose financial ly from the 
publication of this manuscript, either now or in the future?  
 
2.  Do you hold any stocks or shares in an organisation t hat may in any way gain or 
lose financially from the publica tion of this manuscript, either now or in the 
future?  
 
3.  Do you hold or are you currently applying for any patents  relating to the content 
of the manuscript?  
 
4.  Have you received reimbursements, fees, funding, or salary from an organization 
that holds or has applied for patents relating to the content of the manuscript?  
 
5.  Do you have any other financial competing interests?  
 
6.  Do you have any non -financial competing interests in relation to this paper?  
 
If you can answer no to all of the above, write 'I dec lare that I have  no competing interests' 
below. If your reply is yes to any, please give details below.  
 
I have no competing interests  
 
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