Review for 10.1186/s12876-020-01321-z (2020)

Reviewer ’s report  
 
Title: OPTIMIZATION OF IMPEDANCE -MEASURED REFLUX EVENTS IN GORD  
UTILIZING ACID EXPOSURE TIME  
 
Version: 1 Date : 10 Dec 2019  
 
Reviewer: Etsuro Yazaki  
 
Reviewer's report:  
 
The authors intended to tackle discrepancy between oesophageal acid exposure time (AET) 
and the number of gastro -oesophageal refluxes (GOR) in impedance -pH monitoring, which 
are often observed in clinical settings. They  statistically assessed the best cut -off value of the 
number of impedance measured GOR to minimise the inconsistency.  
 
Major comments:  
 
1. The authors calculated the new cut -off value of number of reflux episodes to predict 
AET &gt;4.2% using patients with t ypical or atypical reflux symptoms.  However, this value 
can be one of the indicators to distinguish NERD from reflux hypersensitivity and/or 
functional heartburn, not from asymptomatic healthy subjects. Therefore, "normative value" 
in the title does not s ound appropriate. Normal value should be calculated using 
asymptomatic healthy subjects.  
 
2. For validation of a new cut -off value to diagnose NERD, I would suggest a prospective 
study using patients who have reflux symptoms where you can calculate its rea l sensitivity 
and specificity. Putting the prospective part together with this manuscript, it would make the 
manuscript much more compelling.  
 
Are the methods appropriate and well descri bed?  
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.  
 
No 
 
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 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 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 futu re? 
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 s alary 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 understan d that my name will be 
included on my report to the authors and, if the manuscrip t is accepted f or publication, my 
named report including any attachments I upload will be posted on the website along with the 
authors' responses. I agree for my report to be made available under an Open Access Creative 
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any comments which I do not wish to be included in my named report can be in cluded as 
confidential comments to the editors, which will not be published.  
 
I agree to the open peer review policy of the journa l