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: 28 Dec 2019  
 
Reviewer: Jean M Chalhoub  
 
Reviewer's report:  
 
Interesting idea, especially given the difficulties faced with in -patient colonoscopies.  
The study is well designed and well written.  
 
Here are my comments regarding  the content:  
 
In the "Methods" section  
 
1-in "Trial Design and Setting"  
Correct the first sentence to: "...was approved by the institutional review board..."  
 
2- in "Study Population"  
What about opioid use?  
Was it an exclusion criterion?  
If not, it is kn own to decrease the quality of the prep and it was not compared between patients.  
 
3- in "Bowel Preparation"  
Please list the generic names: polyethylene glycol (PEG), PEG+ascorbic acid, sodium 
picosulfate.  
 
4- in "Procedures"  
Can you please specify the ex act metrics you obtained?  
And regarding ADR, it was not mentioned as an outcome, only cecal intubation was. It is known 
that better prep is associated with higher ADR.  
Was there any difference between the groups (despite the small sample size)?  
In additi on, if you elect to include ADR as part of your analysis / comparison, withdrawal time 
should also be included.  
 
5- in "secondary Outcomes"  
Please summarize the questionnaire content very briefly.  
 
 
 
 
 
 
 
In the "Results" section:  
 
1- The sample size is small and differences may be missed. The fact that around 21% of patients 
taking golytely and that 33% of those taking Moviprep did not finish the prep, might mask a 
better prep outcome with those (larger volume preps) compared to sma ll volume prep.  
Did you compare the scores with those that completed the prep? (sort of a per -protocol analysis?)  
 
2- Can you please summarize your findings regarding nausea and vomiting in the text?  
 
In the "Discussion" section:  
 
1- The 2nd sentence is misleading to readers.  
Please change to: "... low -volume preparation showed a trend towards better BBPS score, 
compared to those receiving larger -volume preparations, but that was not spastically significant."  
 
Again, the issue with the statistical signif icance does not only depend on the sample size. 
Compliance is a major factor and in my opinion, we cannot assume that this is "likely to the 
small sample size". With a bigger sample size, it's worth checking intent to treat vs. per protocol 
(depending on c ompliance)  
 
2-In the second paragraph you can also add the ability to perform dietary changes several days 
prior to colonoscopy (low fiber/low residue diet) which is less likely to happen in the in -patient 
setting.  
 
3- The limitations are very brief and ar e missing. Please expand on that.  
 
The sample size is too small and may mask small differences. There was also no standard diet 
except for the day prior to the colonoscopy (which is a limitation of the in -patient colonoscopy 
but is worth mentioning).  
Plus, you did not mention if patients were on narcotics or not which is a limitation.  
In addition, another limitation is that the ADR was not compared between groups. Even if 
compared, the small sample size would argue against any remarkable / or unremarkabl e result.  
 
In the "Conclusion" section:  
 
Would change the  "...low -volume purgatives may be preferred in the in -patient setting due to its 
better rate and comparable bowel cleanliness when compared to larger volume preparations."  
Please remove the statement about sample size from the conclusion.  
 
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.  
 
Unable to assess  
 
Are the conclusions drawn adequately supported by the data shown?  
If not, please explain in your comments to the authors.  
 
Unable to assess  
 
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.no2.no3.no4.no5.no6.no  
 
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