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: 23 Jul 2018  
 
Reviewer: Guntars Pupelis  
 
Reviewer's report:  
 
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Reviewer report: BMGE -D-18-00351"L ow vitamin D levels are associated with high viral loads 
in patients with chronic „.hepatitis B: A systematic review and meta -analysis  
The manuscript presents meta -analysis to compare the vitamin D levels between patients with 
chronic hepatitis B (CHB) an d healthy controls and to determine whether vitamin D levels were 
correlated with HBV viral loads significantly.  
The purpose of the study is fulfilled partially due to the heterogeneity of the study material. 
Currently the vitamin D deficit is the hot topi c internationally and the beneficiaries of the 
announcements that low levels of vitamin D are wide spreading disregarding the population and 
continents are manufacturers of the vitamin D. However the topic is really important. It is 
difficult to evaluate, even when the literature data are in place, whether ….."Approximately one 
third of world's population has been infected, 70 and over 350 million patients are suffering from 
chronic HBV infection [1 -3]"…..  
The important and well known point is that … "Alth ough there is no consensus on optimal levels 
of vitamin D in serum, a 25OHD 88 level [7, 9]. Vitamin D deficiency results in abnormalities in 
calcium, phosphorus, 90 and bone metabolism".  
It means that the problem is at the worldwide level.  
Some confusion is regarding the controversial statement that: …."No language restrictions were 
applied 114 and the last search was performed on September 28, 2017".  
And…"All the studies 172 were observational studies and were reported as full -text articles in 
English".  
The manuscript otherwise is well prepared and the message is clear.  
The manuscript merits publication in BMC gastroenterology.  
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.  
 
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  
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