Review for 10.1186/s12876-019-1004-2 (2019)

Reviewer ’s report  
 
Title: Low v itamin D levels are associated with high viral loads in patients with chronic hepatitis 
B: A systematic review and meta -analysis  
 
Version: 0 Date: 07 Aug 2018  
 
Reviewer: Yesim Oztas  
 
Reviewer's report:  
 
This may be an interesting meta analysis about the relation between vitamin D levels and HBV 
infection in selected individuals. However the authors need to mak e some revisions so that their 
manuscript can be accepted f  
- Page 4, line 85, reference is needed for other functions of vitamin D.or publication.  
 
- They should mention about the type of the studies either observational or interventional.  
 
- The authors might have some data also from 'Clinical Trials'  
 
- Why didn't the authors include the 15th reference in the metaanalysis?  
 
- Page 11, line 227,,, do the authors really think that they analyzed all available data? This first 
sentence of discussi on should be revised.  
 
- A similar study in the same journal can be  an example for the authors. It is below and it 
should also be cited in the manuscript.  
World J Gastroenterol. 2013 Sep 21;19(35):5917 -24. doi: 10.3748/wjg.v19.i35.5917.Association 
between vitamin D and hepatitis C virus infection: a meta -analysis. Villar LM1, Del Campo JA, 
Ranchal I, Lampe E, Romero -Gomez M.  
 
Are the metho ds 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.  
 
No 
 
Are the conclusions drawn adequately 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 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 recommend additional statistical review  
 
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 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 futu re? 
 
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 a ccepted for publication, my named report  
including any attachments 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://creativecomm ons.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