Review for 10.1186/s12876-017-0696-4 (2017)

Reviewer ’s report  
 
Title:  Non-alcoholic fatty liver disease as a risk factor for cholangiocarcinoma:  A systematic 
review and meta -analysis  
 
Version: 0 Date: 20 Sep 2017 
 
Reviewer:  Jiangbin  Wang  
 
Reviewer’s report:  
 
This meta -analysis focus on the association between NAFLD and CCA, indicating that NAFLD 
may potential increase the risk of CCA and this result is of scientific interest. However, there are 
a number of points that could be addressed for the purpose of impr oving this manuscript.  
 
1. Although widely accepted, funnel plots were not recommended while the number of 
included studies is less than 10.  
 
2. The Egger test and Begger test have been used in this manuscript. Nevertheless, the 
results should be explained with caution, because of the limited number of included 
original studies in this paper.  
 
3. Several subgroup analysis has been performed whil e heterogeneities exist. However, the 
probability of type I errors in the process of hypothesis testing would increase, as a result 
of excessive subgroup analysis.  
 
Are the methods appropriate and well descr ibed?  
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 additional 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:  
 
Acceptable  
 
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 gain or lose financia lly 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 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 y ou 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 an y, please give details below.  
 
'I declare that I have no competing in terests' below.  
 
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 
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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