Review for 10.1186/s12876-023-02796-2 (2023)

Title: Risk factors for inadequate bowel preparation before colonoscopy: a retrospective cohort
study
Version: 3 Date: 03 Sep 2022
Reviewer's report:
I did not comment on most of the English which is adequate for the review but needs to be
cleaned up.
Abstract
The aim of the study appeared to be to look at the season as a risk factor for poor bowel prep.
January 1, 2018 to Dec 31 2018 could be changed to just 2018
You need to describe the preparation in more detail, was it a 3-liter PEG-ELS given as a split
dose?
How was the quality of the bowel prep measured?
Male is an adjective and needs to describe something (male subjects).
The data should be to the 10th not 100th.
You need to use "statistically significant" when describing findings.
INTRODUCTION
"Colonoscopic removal of adenomatous polyps reduces the mortality rate of CRC by 53%
reduction and the risk of CRC within 10 years after colonoscopic polypectomy reduces to that
of general population [5]. "
This sentence is too confusing and the 53% seems low to me. The reference [5] is not appropriate
and you need to cite actual work that has looked at this reduction in mortality.
"in our experience of 5 years I would change to "from 2012 to 2017" or the appropriate date
range.
Was looking the season as a risk factor for poor bowel prep the stated goal of the study when
it was designed?
M+M
How was consent obtained for a retrospective study?
How was bowel prep quality measured? Was there any standardization?
Why could patients not tolerate colonoscopy? Why should they be excluded?
I assume 3 liter PGE powder is 3-liter Polyethylene glycol-3350 (PEG) Electrolyte solution
given as a split dose?
Was the low-fiber diet continued through dinner the day-prior?
I am confused by why another endoscopist would grade the colons if this was a retrospective
study? Did these endoscopists view the procedure live? Did they view a recording of the
procedure? How were they trained to use the BBPS and how was its use standardized?
You should describe the grading scale (or show a small table) for the BBPS and do not need to
describe what segments of the colon were part of the L, TV and R segment scores.
Patients who did not complete bowel preparation were scored as 0 -- needs to be clarified. Did
they undergo a colonoscopy? What if they drank 95% of the prep - did they still get a 0? I am
confused as to how many patients fell into this category and where they are in Fignure 1.
Was there any statistical correction for multiple comparisons?
RESULTS
Table 1 - the definition of an adequate bowel prep and your primary endpoint was each segment
score 2 or 3. You need to show this in the table. You need to stick with percentages that are all
to the 1/10th of a percent.
Why did so many fewer patients undergo colonoscopy during the winter?
What was your definition of the seasons?
You need to remove most of the information in the results paragraph (text of article) since you
show the data in the table. Concentrate on your primary endpoint and statistically significant
findings.
Table 2 should be adequate and inadequate preparations.
Table 3.  inadequate preparations (don't go back and forth with your terms).
DISCUSSION
Needs to present the primary endpoint in the first paragraph.
The meta-analyses belongs in the introduction.
Male > Male gender
You then need to talk about why so few patients had winter colonoscopy, and what might be
different about the patients or their diets in the spring that might make the preps worse.
I find it hard to believe that the quality of a bowel prep would be dependent on the weather.
What is different about spring in your area? Is the diet different? People should be less active in
the winter not spring and so that discussion makes no sense.
How do the demographics of those undergoing colonoscopy in the spring compare to the other
seasons?
Limitations - I am confused as to how you got consent for a retrospective study and how the
quality of the bowel prep was judged. Was bowel prep quality by season the primary end point
of the study when it was designed?
The fact that men and inpatients have worse preps is c/w the published literature.
Why does figure 1 show that a second endoscopy was performed for the inadequate prepped
patients? This is not discussed in the paper. How was their second prep? Was a more intensive
prep used? Should this even be shown?