Review for 10.1186/s12876-020-01264-5 (2020)

Reviewer ’s report  
 
Title: Reduced risk of post ERCP pancreatitis in statin u sers. 
 
Version: 0 Date: 09 Feb 2020  
 
Reviewer: Yousuke Nakai  
 
Reviewer's report:  
This is a retrospective analysis showing the role of statin in reducing PEP.  
The results sugge sted that the use of statin might reduce PEP but the retrospective study design 
has inherent risk of bias.  
 
1. A larger study (PMID: 31895166) reported conflicting results. Please discuss.  
2. The authors may want to use propensity score matched analysis to reduce the risk of bias.  
3. Did those patients on statins take medications on the procedure day? Patients are usually n.p.o. 
on the day of ERCP and don't take unnecessary medications inclu ding statins.  
Was it possible this can affect the outcomes given the half -time of the statins?  
4. Please provide all the variables include in the univariate analyses in methods or results. How 
did you select the variables in the multivariate analysis? Plea se clarify.  
5. Did the authors include all indications of ERCP, both biliary and pancreatic? In general, 
pancreatic duct manipulation can be a risk factor for PEP.  
6. If patients had sphincterotomy at the initial ERCP, those were low risk of PEP at the sec ond 
ERCP. Why don't you include those with native papilla? Or at least, native papilla should be 
include in the analysis.  
7. In the end of Results, please provide OR of no, low and high -statin groups.  
8. Please discuss on the risk of over -fitting.  
9. Figu re 1 was unnecessary.  
 
Are the  methods appropriate and well described?  
If not, please specify what is required in your comments to the authors.  
 
No 
 
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.  
 
No 
 
Are you able to assess any statistics in the manus cript or would you recommend an 
additional statistical review?  
If an additional statistical review is recommended, please speci fy 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 manu script:  
 
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, f ees, 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 t hat may in any way gain or lose 
financially from the publication of this manuscript, eithe r 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 relatin g 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.  
 
none  
 
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I agree to the open peer review policy of the journal