Review for 10.1186/s12876-018-0886-8 (2018)

Reviewer ’s report  
 
Title: Efficacy and safety of chemotherapy after endoscopic double stenting for malignant 
duodenal and biliary obstructions in patients with advanced pancreatic cancer: a single -
institution retrospective analysis.  
 
Version: 2 Date: 27 Nov 2017  
 
Reviewer: Angela Marten  
 
Reviewer's report:  
 
The analysis, data, and conclusion regarding dou ble-stenting are clear, forward and relevant.  
However, the oncological analysis and conclusions are not appropriate. It is unclear from when 
on OS was calculated (time of diagnosis, diagnosis of which stage?), secondly, all therapy lines 
(and chemotherapy regimen) are analyzed asbeing equal which makes no sense. Conclusions like 
'The overall survival time was not significantly different between the patients with chemotherapy 
post double stenting (543 days: IQR 312 -791) and those without chemotherapy (284 da ys: IQR 
207-385)(P = 0.13).' are heavily confounded and inappropriate.  
The authors should skip all statistical analyses on OS, impact of chemotherapy etc and shorten it 
to a pure descriptive section.  
 
Minor:  
T-test analysis sounds improper to me.  
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 co ntrols are required in your comments to the authors.  
 
Unable to assess  
 
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 manuscript or wo uld you recommend an  
additional statistical review?  
If an additional statistical review is recommended, please specify what aspects require further  
assessment in your comments to the editors.  
 
I recommend additional statistical review  
 
Quality of written Eng lish 
Please indicate the quality of language in the manuscript:  
 
Acceptable  
 
Declaration of competing interests  
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holds  or has applied for patents relating to the content of the manuscript?  
 
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below.  If your reply is yes to any, please give details below.  
 
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