Review for 10.1186/s12876-020-01457-y (2020)

Review er’s report  
 
Title: Underwater versus conventional endoscopic mucosal resection  for small size 
nonpedunculated colorectal polyps ：A randomized controlled trial  
 
Version: 0 Date: 06 May 2020  
 
Reviewer's report:  
 
This manuscript presents describes the efficacy of underwater endoscopic mucosal re section 
comparing with conventional manner. Authors conducted randomized control study to 
demonstrate this issue, and its methodology seems to be straightforward.  
 
However, I would like to ask authors to address some concerns.  
 
 
1. Regarding with sample si ze, its calculation should be based on the primary endpoint of 
the study. Authors mentioned that the primary endpoint were complete resection rate and en 
block resection rate. However, sample size was calculated from the previous data related with 
recurren ce rate. If they meant same thing, I believe it better to unify these descriptions.  
 
2. More detail regarding the minimization method used in randomization should be 
provided, and all variables used in minimization should be adjusted for in the final analy ses. 
 
3. How many endoscopists participated in this study? How about the degree of experience 
for endoscopic treatment among them? I guess it should be included in the allocation factors.  
 
4. All resected lesions were macroscopically recorded as 0 -I type lesion and no 0 -IIa type 
lesions was seen. Is it real? There seems to be some sessile serrated adenomas or hyperplastic 
polyps that often described as 0 -IIa type lesion. Moreover, some previous  studies objecting small 
or diminutive colorectal polyps, there might be even number of 0 -IIa type adenomas.  
 
5. I understand that there is no significant difference between CEMR and UEMR from 
this study, then how should I use properly? I would like to ask  authors to discuss about it in 
DISCUSSION section.  
 
 
Minor comment  
In Table 2, is this miss type?  
Median size , (IQR, second)→Median size, (IQR, mm ） 
 
Are the methods appropriate and well described?  
If not, please specify what is required in your c omments 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 yo ur comments to the authors.  
 
Yes 
 
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 y our 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, f ees, funding, or salary 
from an organisation that may in any way gain or lose financial ly from the 
publication of this manuscript, either now or in the futur e? 
 
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, 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 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 competin g interests' 
below. If your reply is yes to any , please give details below.  
 
I declare that I have no competing interests  
 
Reviewer Publication Consent. I agree for my report to be made  available under an Open 
Access Creative Commons CC -BY License ( http://creativecommons.org/licenses/by/4.0 ) if this 
manu script is accepted for publication. Any comments that I do not wish to be included in the 
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I agree to the terms of the CC -BY 4.0 license; please do not publish my name with my report.  
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