Review for 10.1186/s12876-021-01732-6 (2021)

Reviewer’s report
Title: 
Association between surgical volumes and hospital mortality in patients: a
living donor liver transplantation single center experience
Version: 
0 
Date: 
27 Dec 2020
Reviewer's report:
In this manuscript Hsieh et al. present a retrospective, single center cohort study
analyzing the mortality in patients after living donor liver transplantation in
order to find prognostic factors influencing postoperative prognosis. They found
that donor age, blood loss and center volume <30 LDTD/year negatively impact
the outcome. 
I read this manuscript with interest and I have several questions/comments to the
authors:
Introduction section:
- This section is somewhat short 
Methods section:
- To have a homogenous group I suggest to exclude combined liver and kidney
transplantation from the analysis
- The description of surgical technique is not necessary for this study - I would
give only reference (described elsewhere etc.)
- Please change Re-operative to re-operation
- As you used Olthoff criteria for early allograft dysfunction I suggest to use this
term (EAD) instead of delayed graft function
- The sentence on page 5 lines 29-31 can be omitted as it is also in the result
section. Next two sentences should be placed in the section describing statistical
analysis 
Result section:
- In the multivariate analysis the authors entered also factors that has not been
significant in the univariate analysis (bilirubin, creatinine), which is
contradictory to their statement in the statistical section. Could you explain this?
- When you compare the outcome of LDLT between the two different annual
volumes have you found different risk factors for mortality between these
groups?
Discussion section:
- Discussion is too long. I would exclude detailed description of the
postoperative complications, but rather discuss your findings in the light of
existing literature
- The conclusion needs to be concise and to the point
General comment: the manuscript needs a revision regarding English accuracy
(syntax, etc.)
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Is the study design appropriate to answer the research question (including the use
of appropriate controls), and are the conclusions supported by the evidence
presented?
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from apparent manipulation?
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