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

Title: Risk factors for inadequate bowel preparation before colonoscopy: a retrospective cohort
study
Version: 5 Date: 07 Jan 2023
Reviewer's report:
TITLE
Risk factors of inadequate bowel preparation before colonoscopy: a retrospective cohort study
Should be
Risk factors for inadequate bowel preparation before colonoscopy: a retrospective cohort study
ABSTRACT
Much improved but still needs work
"In this retrospective study, patients who underwent colonoscopy during 2018 were included.
Patients received 3 L of Polyethylene Glycol Electrolytes powder. "
Should be
In this retrospective study, patients who underwent colonoscopy in 2018 and received 3 L of
Polyethylene Glycol Electrolytes powder were included.
Delete "There were 3467 (51.6%) male patients. " it is not important enough to be in the abstract.
"Using winter as a reference, patients in spring had a worse bowel preparation, while patients in
summer were more easily to have adequate colon preparation. There is no statistically significant
difference between bowel preparation in autumn."
does not make sense. It just says the same thing your numbers say.
You need to say:
and season (give stats here and what you are comparing, spring vs  the other 3 seasons) were the
independent risk factors for inadequate bowel preparation.
"Compared with autumn and summer, patients in spring may need intensive bowel preparation.
Male patients and inpatients should receive more enhanced instructions for bowel preparation."
Your conclusions are inconsistent.
1) Why spring vs. autumn and summer (why not winder)?
2) why do spring preps need a "intensive bowel prep" while male patients and inpatients  receive
more enhanced instructions for bowel preparation? You do not present data as to what about
the preps that caused the inferior results in spring. The statement should be more general such
as "enhanced" or "intense"
INTRO
"day-before" should be day-prior
"we observed that the quality of bowel preparation for the same patient varied in different
seasons. " remove "for the same patient".
"To the best of our knowledge, we performed this study, a first of its kind, to analyze the risk
factors for inadequate bowel preparation before colonoscopy."
should be
"To the best of our knowledge, this is the first study to analyze the season as a risk factor for
inadequate bowel preparation before colonoscopy."
M+M
Again how do you get informed consent for a retrospective study?
Thye gave consent for the colonoscopy, no the study.
"On the day of appointment, " should be during an appointment prior to the colonoscopy
", and eating was forbidden the night before colonoscopy." needs to be clarified, for example
"and eating was forbidden after 6 PM the night before colonoscopy".
"All patients were prescribed a standard split-dose preparation regimen based on 3 L PGE
Powder (#) (Beijing Staidson BioPharmaceuticals Co. Ltd., Beijing, China) plus simethicone
(30mL, Zigong honghe pharmaceutical co. Ltd., Szechwan, China). Patients received 3 L of
Polyethylene Glycol Electrolytes powder. They were instructed to drink half of the volume the
night before colonoscopy, and the other half was given in divided doses of 250 ml every 10
minutes 4-6 hours before the procedure. All patients received 30 ml of simethicone 4-6 hours
before colonoscopy."
should be
"All patients were prescribed a  split-dose preparation of 3 L PGE Powder (#) (Beijing
Staidson BioPharmaceuticals Co. Ltd., Beijing, China) plus simethicone (30mL, Zigong honghe
pharmaceutical co. Ltd., Szechwan, China) given as follows:  1.5 liters the night before
colonoscopy, and 1.5 liters given in divided doses of 250 ml every 10 minutes 4-6 hours before
the procedure with 30 ml of simethicone 4-6 hours before the colonoscopy. Patients consuming
other preparations were excluded from the study"
"The primary endpoint was an adequate preparation defined by the BBPS with each segment
score # 2. Sufficient bowel preparation was defined as BBPS # 6 with each segment # 2 [15],
the rating is after cleaning maneuvers are performed. "
should be
"The primary endpoint was an adequate preparation defined by all 3 BBPS segment scores # 2. "
"The BBPS was rated from 0 (inadequate) to 3 (excellent) for each segment (left, transverse, and
right) of the colon. The points are assigned as follows, 0: mucosa not seen due to solid stool that
cannot be cleared; 1: portion of mucosa of the colon segment seen, but other areas of the colon
segment not well seen due to staining, residual stool and/or opaque liquid; 2: minor amount of
residual staining, but mucosa of colon segment seen well; 3: entire mucosa of colon segment
seen well [16]. " add "with the rating assigned after cleaning maneuvers are performed"
My questions from last time> Was season the primary endpoint of the study when it was
designed?
Your Response: Thank you for your helpful comment. As you said, we found that season may
be an influencing factor of poor intestinal preparation through clinical
observation, so we took season as one of the variables in our data statistics
The study end points are really your multi-variable analysis of risk factors for inadequate
preparations as defined by BBPS segments all >=2.
I think you need to list the variables you planned to analyze when the study was designed and
if that included season. Was season something you added after you had the data and noted it
was statistically significant?
Most studies describe a primary endpoint and secondary endpoints before the study is
undertaken. For example, if you have 20 endpoints you evaluate, then, just by chance alone, one
is likely to be positive at a 0.05 level.
It needs to be clearly stated in the design of the study what the
RESULTS
Patient characteristics > how many were excluded because they did not consume 3 L of
Polyethylene Glycol Electrolytes powder?
The highest number of colonoscopies were performed in summer #### (32.2%), followed by
spring #### (28.0%), autumn ####(28.0%) and winter #### (11.8 %).  add the number for each
season to be consistent.
TABLE 2
Same comments as before:
1) Total BBPS scores should be presented as mean +- SD. If you wish to list all 10 potential
scores (0 to 9) you can do that. Your arbitrary categories (4-5, 7-8) are not appropriate. The
words (poor, fair, etc) are not appropriate.
2) Adequate vs. inadequate is the primary endpoint of your study and should be in the table (all
3 segments>=2).
3) segment scores should also be presented mean+- SD.
4) State multiple findings possible since the total is over 100%.
"The BBPS score of #3 and 4-5, 6, 7-8 and 9 were observed in 141 (2.1%), 405 (6.0%), 5525
(82.3%), 512 (7.6%), and 137 (2.0%) cases respectively" needs to be deleted.
TABLE 3
Your percentages are wrong. For example, constipation CC for those with adequate bowel preps
is 361/6149=5.9% (not 90.9% which is an irrelevant calculation of 361/(36+361).
Same comments with all the other % calculations in this table.
I had this same comment last time and it needs to be fixed.
You need to state "Colonoscopic findings (multiple findings possible)" or something similar
since the total is more than 100%.
"Considering winter as the reference point, patients undergoing colonoscopy in spring had
worse bowel preparation (OR: 1.514; 95% CI: 1.139-2.012; P=0.004), while patients receiving
colonoscopy in summer had better bowel preparation (OR: 0.738; 95% CI: 0.546-0.948;
P=0.050) " an shorter version of this should be in the abstract.
DISCUSSION
Much improved.
Age should start a new paragraph.
"Perhaps the most important finding we identified in this study was that the season was an
independent risk factor of inadequate bowel preparation. " I agree with that. Why not start the
discussion with this finding?
"The exact season for this observation is not known." you mean reason not season.
"However, the number of cases included in this study was large and no previous articles on
season and intestinal cleanliness have been published. "
should be
"However, the number of subjects included in this study was large and no previous articles have
looked at the season as a risk factor for inadequate cleansing for colonoscopy. "
My comments 27. 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. Response: Your response> Thank you
for your insightful comment. As you said, the quality of bowel
preparation in our study is not very good. We choose Polyethylene Glycol Electrolytes
(PGE) Powder (#) and simethicone oil because they are relatively cheap, so they are widely used
in our area. Therefore, we selected these patients for statistical analysis. Thank you again for
your valuable advice.
This needs to be discussed in the paper under limitations.
I it likely these findings would apply with other preps? Outside your area of China? In the rest
of the world?