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

Title: Risk factors for inadequate bowel preparation before colonoscopy: a retrospective cohort
study
Version: 4 Date: 16 Nov 2022
Reviewer's report:
The English will need some editing but is adequate for this review.
It would be easier to read if paragraphs were indented (tab first character).
Abstract
"Polyethylene Glycol Electrolytes Powder (#) + simethicone" You need to state 3-liter
Polyethylene Glycol and electrolyte solution given as a split dose (simethicone would be nice
to add if you have room).
"The primary outcome was the Boston Bowel Preparation Scale score" - the primary outcome
was an adequate bowel preparation defined as all 3 segments rated 2 or 3 on the Boston Bowel
Prep scale.
49.7±13 years old = you need to be consistent and all numbers go to the 1/01th.  13.0 or 13.1
It's not a poor bowel prep - it is either adequate or inadequate.
"Male subjects" should be male gender
INTRODUCTION
Was season the primary end point of the study when it was designed?
M+METHODS
"received Polyethylene Glycol Electrolytes (PGE) Powder (#)+ simethicone" this need to be
clarified?
Did other patients get a different prep and were excluded from the study?
at what time did the low-fiber diet end?
The primary endpoint was an adequate preparation defined by the BBPS with each segment
score # 2.
You also need to make it clear that the rating is after cleaning maneuvers (washing)  are
performed.
RESULTS
"patients were males" is patients were men. Male is an adjective and describes a noun.
"Most patients (57.1%) had colonoscopy in the afternoon, while 2885 (42.9%) patients
underwent colonoscopy in the morning" - your description are inconsistent with some
percentages and some numbers and some both. You need to incloude both.
"Most patients xxxx (57.1%) had colonoscopy in the afternoon, while 2885 (42.9%) patients
underwent colonoscopy in the morning"
The detailed baseline characteristics are presented in Figure 1.  The bottom row with "allocation"
is not correct, this is part of results and should not be part of this table. This was not part of
the prestudy allocation.
"Highest number of colonoscopies were performed in the summer season (32.2%). The
number of colonoscopies performed in spring, autumn, and winter were 1883, 1882, and 791,
respectively. " same comment as above.
"Positive findings were detected in 3470 colonoscopies. The BBPS score of #3 and 4-5, 6, 7-8
and 9 were observed in 141 (2.1%), 405 (6%), 5525 (82.3%), 512 (7.6%), and 137 (2%) cases
respectively. In the right-sided colon, BBPS scored 0 in 35 (0.5%), scored 1 in 385 (5.7%), 2 in
6069 (90.3%), and 3 in 231 (3.5%) patients. In transverse colon, BBPS scored 0, 1, 2, 3 in 18
(0.3%), 257 (3.8%), 6140 (91.4%), 305 (4.5%) cases, respectively. And in the left-sided colon,
BBPS scored 0, 1, 2, 3 in 24 (0.4%), 210 (3%), 5929 (88%), 577 (8.6%) patients, respectively. "
For the text do not just repeat what you have in your tables. Highlight the statistically significant
results and comment on the primary endpoint.
This is the heart of the results and needs to be presented more clearly. Table 1 has your results,
but also includes baseline characteristics. Baseline information such as age, sex, time season
goes in one table. The results go in a second table.
Your bowel preparations are adequate and inadequate, the other terms do not belong (fair, poor).
The total score is not relevant since your primary endpoint is all 3 segments scored 2 or 3.  The
primary data needs to be presented. Your total BBPS score is not the primary data and the way
you broke down the scores (0-3, 4-5, etc) is arbitrary. If you wanted to give total scopes from
0 to 9 you could, it is only 5 more lines.
You also need to present mean +-SD for the Total BBPS score since this is what is reported
in virtually every bowel prep paper and will give another important measurement of your prep
quality (even if not the primary endpoint).
The breakdown by segment is nice and I note that most of your subjects had BBPS segment
scores of 2 with very few with 3. This is c/w suboptimal preparation since most better quality
preparations have a much higher percentage of segment scores of 3.
Table 2 has numerous errors with the percentages miscalculated. Again, you need to use 1/10th
of a percent - 6.0% not 6%.
The detailed baseline characteristics are presented in Figure 1.  The bottom row with "allocation"
is not correct, this is part of the results and should not be part of this table.
Male gender (not subjects)
DISCUSSION
"Colonoscopy is the most important tool for the diagnosis and treatment of colonic diseases [17,
18]. Inadequate bowel preparation not only affects the accuracy of colonoscopy, but also has a
detrimental effect on other aspects of the colonoscopy, including cecal intubation failure, need
for repeated procedures, longer hospital stays, and increased healthcare costs [19-21]. Therefore,
determining the risk factors for poor colon preparation would help in providing more intensive
bowel preparation to the subjects. " - this is part of the introduction and should not begin your
discussion.
You need to start with something like this:
"our retrospective study of XXXX subjects undergoing colonoscopy in 2018 showed ... then
talk about your primary endpoint and what is statistically significant."
Discussion of that endpoint. That is really the one finding that makes your study worth
considering for publication. The other stuff is largely confirming what has been reported
numerous times by others.
Is your information applicable to the rest of China and the world? You have different numbers
of patients undergoing colonoscopies in different seasons while most centers have a more steady
business throughout the year. Do you think this is a local phenomenon or an unrecognized issue
in the rest of the world?
Present secondary endpoints, is usually best for each to have its own paragraph if you are also
going to discuss it.
Discussion of those endpoints.
The overall quality of your preps is not great. This could be discussed as well. Highly efficacious
bowel preps will give you adequate preparations in 95-99% of subjects (Moviprep split, SuPREP
split, high dose Gatorade and PEG-3350). Most better preps give you many more segment scores
of 3.