Review for 10.1186/s12876-020-01373-1 (2020)

Reviewer ’s report  
 
Title: Effect of Bowel Preparation Volume in Inpatient Colonoscopy. Results of a Prospective,  
Randomized, Comparative Pilot Study  
 
Version: 0 Date: 24 Nov 2019  
 
Reviewer: David kastenberg  
 
Reviewer's report:  
 
This small pilot study addresses a gap in medical care - the clear need to optimize inpatient colon 
preparation. The study compares three commercially available FDA approved purgative - 4L 
PEG -ELS, 2L PEG -ELS with high dose vitamin C, and 300 ml Mg Citrate/bisacodyl. All were 
administered as a split dose, and all  patients were on clear liquids the day prior.  
 
Major issues  
 
* This is a very small pilot and would not overreach with any conclusions about efficacy 
or tolerance. It is interesting that the low volume preparation did not clearly perform worse, and 
theref ore may be worthy of a properly powered study.  
 
* In terms of conclusions of efficacy and tolerance, this study looked at one particular 
low volume preparation and the findings may not be generalizable. Taste, prep completion, and 
adverse events may differ with other low volume options.  
 
* As acknowledged by the authors, it is important to stress that no FDA approved 
purgative is "approved" for vulnerable populations such as CHF, advanced renal disease, 
decompensated liver disease, etc. PEG -ELS is the default  choice for such patients. The inpatient 
population has more patients with such conditions, and the potential for prescribing error in such 
patients should be considered.   
  
Minor issues  
 
* Were other factors known to increase the risk for inadequate prep considered - 
tricyclics, neurologic disease, opioid use, prior inadequate prep, etc.?  
 
* How much prep was actually consumed in the other groups? Can the authors provide 
more than completed vs. did not complete?  
 
* How many preps in each group were adequate  as defined by BBPS &gt; 6 in each 
segment?  
 
* How many preps were "clinically" inadequate for the purpose of the colonoscopy such 
that a repeat was needed?  
 
* It seems unusual that no patients were withdrawn. All patients randomized completed 
the study? No  cases were cancelled prior to colonoscopy for any reason?  
 
Comments  
 
* In this study all patients got clear liquids the day prior, but in real life often that doesn't 
happen depending on when the decision for colonoscopy is made.  
 
* Preps other than PEG -ELS cannot be used when a rapid prep is needed as they require 
splitting.  
 
* Fellows were involved with the procedures. I can understand the Attending being 
blinded, but the Fellows involved in the details of patient care were always fully blinded? I 
presume the Fellow did the report and created the BBPS?  
 
* The authors may want to  expand the section on limitations.  
 
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 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 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.  
 
1) Have advised Ferring within the past 5 years on advisory b oard2) Have advised MotusGI and 
done research regarding a device to cleanse the colon in patients with inadequate preparation3)  
Have advise d Salix within the last 5 years on advisory board  
 
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