Review for 10.1186/s12876-018-0797-8 (2018)

Reviewer ’s report  
 
Title: The early outcomes of candidates with portopulmonary hypertension after liver  
transplantaion  
 
Version: 0 Date: 15 Mar 2018  
 
Reviewer: Quirino Lai  
 
Revie wer's report:  
The early outcomes of candidates with portopulmonary hypertension after liver transplantation: 
A Meta -analysis (BMGE -D-18-00130)  
 
This is an interesting meta -analysis from China based on 37,729 patients undergoing liver 
transplantation aimed a t investigate the prognostic role of porto -pulmonary hypertension (PPH) 
in this specific population.  
The study is of interest and it is well done from a statistical point of view.  
I have some comments:  
1) English style surely needs an accurate revision, because several errors can be found across the 
entire text.  
2) The analysis investigating the risk for 30 -day death after transplant is bases on few cases, so 
such a limit should be clearly reported: it is in fact difficult to definitively say that PPH plays a 
detrimental role in terms of 1 -year patient and graft survival but not after 30 days from transplant 
only basing on the small samples investigated in this latter analysis.  
3) As for the meta -analys is investigating the graft loss rate, I2 is >50. Thus, an error is present in 
the text, in which it is reported that no heterogeneity is present among the analysed papers. I 
think only the random effect model should be reported in this case, eliminating th e results of the 
fixed effect model.   
4) Another shortcoming of the paper is that the different grades of PPH severity are not reported 
in the different papers, and that the differences among the reported studies should be also 
influenced by different inc idences of less or more severe PPH. This consideration must be added 
in the section dedicated to the limits of the paper.  
5) EMBASE, Cochrane Library and PUBMED were analyses, but the Figure 1 does not entirely 
report the characteristics of the PRISMA flo w-chart: how many duplicates were removed?  
6) No quality of the different articles has been reported: I think the Newcastle -Ottawa Scale 
should be used for giving a grade of quality for each study.  
7) In the title there is a typo: transplantaion is obviou sly transplantation.  
 
Are the methods appropriate and well described?  
If not, please specify 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.  
Yes 
Are the conclusions drawn adequately supported by the data shown?  
If not, please explain in your comments to the authors.  
Yes 
 
Are you able to assess any statistics in the manuscript or would you recommend an 
additional statistical review?  
If an addition al statistical review is recommended, please specify what aspects require further  
assessment in your comments to the editors.  
I am able to assess the statistics  
Quality of written English  
Please indicate the quality of language in the manuscript:  
Not suitable for publication unless extensively edited  
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 salary from an  
organisation that may in any way ga in or lose financially from the publication of this  
manuscript, either now or in the future?  
2. Do you hold any stocks or shares in an organisation that may in any way gain or lose  
financially from the publication of this manuscript, either now or in the f uture?  
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 declare that I have no competing interests' 
below. If your reply is yes to any, please give details below.  
'I declare that I have no competing interests'  
I agree to the open peer review policy of the journal. I understand that my name will be included 
on my report to the authors and, if the manuscript is accepted for publication, my named report 
including any attachmen ts I upload will be posted on the website along with the authors' 
responses. I agree for my report to be made available under an Open Access Creative Commons 
CC-BY license ( http://creativecommons.org/licenses/by/4.0/ ). I understand that any comments 
which I do not wish to be included in my named report can be included as confidential comments 
to the editors, which will not be published.  
I agree to the open peer review policy of the journal