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

Reviewer ’s report  
 
Title: Evaluation of Risk Factors for Perforated Peptic Ulcer  
 
Version: 0 Date: 07 Sep 2017  
 
Reviewer: Hyunghun Kim  
 
Reviewer's report:  
 
I. General view  
 
Dear Authors  
 
 
First, I would like to cheer up authors' effort for this result. I know how hard it is. However, there 
are many points that I would like to ask about authors' paper.  
 
In General, please write authors paper in detail especially in method and result section. I read 
again and again to find out missing word (in my opinion). Please do not make readers suspicious 
of something during reading authors' paper. The logic should be like water flow from the 
mountain to the ocean. Please keep in mind that if you find some thing weird in your paper, it 
should be investigated deeply and should be explained. Then please check many things that I 
suggested you. I am looking forward to listening authors' logics and reasoning.  
 
 
 
II. Specific points  
 
Abstract  
 
# All data such as pas t medical histories, physical findings, and laboratory data were collected 
[though?] chart reviews. I conjecture that though may be through? Please check it  
 
 
Introduction  
 
# The introduction is somewhat complicated. Please make it more concise, for example , you do 
not need to narrate all details accompanied with PUD. You need to focus on PPU.  
 
 
 
Method  
 
# Please describe method section as delicately as possible. It is very important  
 
# Authors described "In contrast, we considered those patients who were subj ected to an 
abdominal CT scan at dates close to the scans of case subjects but were diagnosed with diseases 
other than PPU and had the same demographics, including exact age and gender, as potential 
control subjects."  
 
Have authors ever thought of 1:3 case -control comparison? You used 1:2 (136:272) situation. It 
is Ok, but 1:3 might increase the statistical power. Did you select 1:2 due to not enough PPU 
patients? Please let me know.  
 
 
# Why did you use four models?  
 
# Dear Authors… I would like to listen to authors' opinion about ROC (Fig 1). Would you please 
describe the accurate title of ROC? I cannot understand what this curve means when I watch this 
tile. As you know ROC curve needs two responsive variables and one explanatory variable. Is 
ROC curve about  muscular defense or PUD history? The suggested significant factors were 
muscular defense and PUD history. Do you have any scale about this variables in common 
clinical practice in authors' hospital? I understand that this is a retrospective study "A 
retro spective case control study was conducted between August 2004 and March 2016 at St. 
Luke's International Hospital"  
 
 
 
Result  
 
Result  
 
# Please describe result as delicately as possible.  
 
# In table 1 and table 2, I found out that some variables are significant in Multivariate analysis 
but not significant in Univariate analysis. This phenomenon might be caused by following four 
reasons; (1) the effect of unbalanced sample size; (2) the infl uence of missing data; (3) an 
extremely large within group variation, relative to between group variation; and (4) the presence 
of interaction. Please describe authors' view on this statistical phenomenon in authors' paper.  
 
# In table 2, many statistical results are missing. I would like to ask authors why?  
Discussion  
 
# Authors described "There were some differences in the prediction factors between PUD and 
PPU. For one, anticoagulants were thought of as a prediction factor for PUD, increasing the OR 
to 1.98 15, but anticoagulants did not increase the risk of PPU in our study. We hypothesized that 
the insignificance of anticoagulant drugs was due to their mechanism. Unlike Cox -1 inhibitors, 
anticoagulants are medications which inhibit the productions of f ibrin at the end of the blood 
coagulation reaction 16 ; they may promote the bleeding risk, but may not cause damage to the 
gastric mucous membrane."  
 
In my opinion, authors' explanation seems not so persuasive. I agree that anticoagulant does not 
cause mu cous membrane damage directly, however it can prohibit rapid healing of damaged 
mucosa and consequently can contribute perforation process because coagulation is also the 
defense mechanism prohibiting progression of PUD. As you know, out body is homeostati c 
status; damage & repair, damage & repair, & damage & repair… I do believe the breakdown of 
homeostasis may substantially contribute from ulcer to perforation. I would like to listen to 
authors' opinion.  
 
# Authors described "increase in platelet count wa s statistically significant in PPU, and could be 
used as a prediction factor. Platelets are component of blood, necessary to arrest bleeding, thus 
thrombocytopenia is known cause of bleeding. In our PPU study, however, platelet counts were 
significantly in creased. We presumed that peritonitis caused inflammation and perforation 
stimulated coagulation; therefore, platelet counts were increased especially in the PPU patients."  
 
Do you think this is the logical explanation? You said that thrombocytopenia is kno wn cause of 
bleeding, AND said stimulated coagulation is the cause of thrombocytopenia. Would you please 
show logically missed explanation to make me understand?  
 
 
Conclusion  
 
# I do believe that the conclusion should be concise with gist information, but authors' 
conclusion is very obscure. I believe that most physicians know that they need APCT when PPU 
is suspicious. I think the reasonable concise conclusion from authors' paper would be "When a 
physician find out muscular defense and PUD history APCT wou ld be necessary for diagnosing 
PPU" if I accept all method and results of this paper. Please keep in mind that the conclusion 
should not be obscure or too long.  
 
 
Thank you for reading long comments  
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 recommend additional statistical review  
 
Quality of written English  
Please indicate the quality of language in the manuscript:  
 
Needs some lan guage corrections before being published  
 
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 
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 al l 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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