Review for 10.1186/s12876-018-0855-2 (2018)

Reviewer ’s report  
Title: Propensity score -matching analysis to compare clinical ou tcomes of endoscopic 
submucosal dissection for early gastric cancer in the postoperative and non -operative stomachs  
 
Version: 0 Date: 14 Jun 2018  
 
Reviewer: Takuji Gotoda  
 
Reviewer's report:  
This is a fi rst study to evaluate the technical outcomes of ESD comparing post -operative stomach 
with non -operative stomach using propensity score matching. Although it is an interesting topic, 
several changes are needed to improve the overall quality of this manuscri pt. 
 
1. In discussion, you discussed about the necessity of additional surgery after non -curative 
resection in post -operative stomach, comparing its perioperative risk with its lymph node 
metastasis risk. Resent report suggested useful scoring system for ev aluating the risk of lymph 
node metastasis (Hatta et al. Am J Gastroenterol. 2017; 112(6):874 -81). You should discuss 
the predicted risk of lymph node metastasis for non -curative patients in ESD -P group using 
this scoring system.  
2. In abstract, you used " The primary endpoint" and "Secondary endpoint". However, these seem 
to be inappropriate because this was a retrospective study. Please change "endpoint" to 
"outcome" in manuscript.  
3. In statistics, you defined Experts as those with experience performing 5 0 or more ESD 
procedures. Please show the reason of this definition.  
4. In method, the difference of electrosurgical units (VIO300D or ICC200) might affect the 
outcomes. Please consider to include it to one of covariates for propensity score matching. Or 
please comment on this point in discussion.  
 
Are the methods 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 adequa tely 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 manus cript or would you recommend an 
additional statistical review?  
If an additional statistical review is recommende d, 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 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 a ny way gain or lose financial ly 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, 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 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 accepted for publication, my named report 
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which I do not wish to be included in my named report ca n be included as confidential comments 
to the editors, which will not be published.  
 
I agree to the open peer review policy of the journal