Review for 10.1186/s12876-018-0756-4 (2018)

Reviewer ’s report  
 
Title: Evaluation of Risk Factors for Perforated Peptic Ulcer  
 
Version: 1 Date: 07 Dec 2017  
 
Reviewer: Hyunghun Kim  
 
Reviewer's report:  
 
Dear Authors  
 
 
 
I appreciate your effort to re vise your manuscript according to the request and would like to ask 
some more questions.  
 
 
No 1  
 
To my Comment 8 [In table 1 and table 2, I found out that some variables are significant in 
Multivariate analysis but not significant in univariate analysis. Th is phenomenon might be 
caused by following four reasons; (1) the effect of unbalanced sample size; (2) the influence of 
missing data; (3) an extremely large within -group variation, relative to between -group variation; 
and (4) the presence of interaction. P lease describe authors' view on this statistical phenomenon 
in authors' paper], Authors replied as follows "Moreover, the phenomenon which some variables 
are significant in multivariate analyses but not significant in univariate analysis is mainly coming 
from confounding factors."  
 
I would like to ask why authors thought that this result came from confounding factors. How can 
authors explain that this statistical consequence did not come from any of (1) the effect of 
unbalanced sample size; (2) the influenc e of missing data; (3) an extremely large within -group 
variation, relative to between -group variation.  
 
 
No 2  
 
To my Comment 11 [Authors described "increase in platelet count was statistically significant in 
PPU, and could be used as a prediction factor. Platelets are the component of blood, necessary to 
arrest bleeding, thus thrombocytopenia is the known cause of bleeding. In our PPU study, 
however, platelet counts were significantly increased. We presumed that peritonitis caused 
inflammation and perforation stimulated coagulation; therefore, platelet counts were increased 
especially in the PPU patients." Do you th ink this is the logical explanation? You said that 
thrombocytopenia is the known cause of bleeding AND said stimulated coagulation is the cause 
of thrombocytopenia. Would you please show logically missed explanation to make me 
understand?], Authours replie d as follows ""We presumed that peritonitis caused inflammation 
and perforation stimulated platelet aggregation; therefore, platelet counts were increased 
especially in the PPU patients."  
 
 
I would like to ask authors to re -consider this phenomenon as the r esult of "reactive 
thrombocytosis".  
 
I will wait for your reply.  
 
Thank you.  
 
 
 
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 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 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 recommend additional statistical review  
 
Quality of written English  
Please indicate the quality of language in the manuscript:  
 
Accep table  
 
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, fees, funding, or sa lary from an 
organisation that may in any way gain or lose financial ly from the publication of this 
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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?  
 
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below. If your reply is yes to any, please give details below.  
 
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