Review for 10.1186/s12876-020-01339-3 (2020)

Reviewer ’s report  
 
Title: The Risk of Rheumatoid Arthritis among Patients with Inflammatory Bowel Disease: A  
Systematic Review and Meta -analysis  
 
Version: 0 Date: 21 Feb 2020  
 
Reviewer: Mostafa Shalaby  
 
Reviewer's report:  
 
I would like to thank the authors for this important manusc ript which try to highlight an 
association between RA and IBD. The manuscript well -written and structured. I have certain 
comments and question which could enrich the manuscript.  
 
Introduction:  
Q1: at the end of introduction the authors mentioned they aim ed on highlighting the association 
and the mechanism between RA and IBD, however, the mechanism covered only in discussion 
section with a single paragraph, is there any other evidence generated from the meta -analysis 
regarding this point?    
 
Methods:  
Q2: the authors screened the important databases Pubmed, Emabse, and Web of Science, why 
the authors excluded Cochrane central?    
 
 
Results:  
Q3: could the authors describe the population included in meta -analysis; total number of 
patients; gender distribution ; age; UC/CD numbers and any possible data?  
 
Q4: On page 8 paragraphs starting from line 160 could the authors insert the references of 
studies?  
 
Q5: are there any possibility to run subgroup analysis based on gender; duration of studies; 
disease condition s; or interventions? I know these are retrospective data which limit extraction of 
all required information, however, if this possible it will add great information  
 
Q6: could the authors run a meta -regression model to report causes of the heterogeneity?  
 
Discussion:  
Q7: the authors wrote an important paragraph on page 10 line no 215; about the confusion 
between RA and arthritis, could the authors summarize the definitions or diagnostic criteria 
employed in the included studies? even this could be importan t for future studies  
 
Kind regards              
   
 
Are the methods appropriate and well described?  
If not, please specify what is required in your comments to the au thors.  
 
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 c omments 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 recommend additional statistical review  
 
Quality of written English  
Please indicate the quality of language in the manuscript:  
 
Needs some language corrections before being published  
 
Declaration of competing interests  
Please complete a declaration of competing in terests, 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 t he 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 th e 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 y ou 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'  
 
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