Review for 10.1186/s12876-025-03707-3 (2025)

Title: Comparing the bowel cleansing efficacy between sodium picosulfate vs. 2L polyethylene
glycol electrolyte lavage solution for colonoscopy: A prospective observational study
Version: 2 Date: 28 Nov 2024
Reviewer's report:
Major imp[improvements, but still some work to do.
Title
I do not like the title and do not think "real-world" belongs. My suggestion:
A prospective observational study comparing the bowel cleansing effects of sodium picosulfate
vs. 2L polyethylene glycol electrolyte lavage solution for colonoscopy
Abstract
I do not think you need "real-world setting". The fact that the study is prospective and
observational says it all.
"as assessed by the Boston Bowel Preparation Scale (BBPS)" with all segments 2 or 3.
You are not consistent with your use of PEG or PEG-ELS.
I would remove the following from the abstract
"Although there were no significant differences in the total BBPS score between the two groups,
the BBPS score of the right colon was significantly higher in the PICO group [(2.15 ± 0.53) vs.
(2.11 ± 0.51), P=0.005]. In addition, adverse reactions differed between the groups, the" Your
abstract need to concentrate on the primary end point of the study. If you chose, you could add
"there were no significant differences in the total BBPS score between the two groups"
"In this real-world study" should be "In this prospective observational study"
"regimens achieved adequate bowel preparation "  this is not acceptable. You need to describe the
primary end point from your study, MAYBE both >90% or no statistically significant differences
between.
BACKGROUND
You are too loose with the term PEG. It is PEG-ELS in your usage. PEG alone generally suggests
pure PEG-3350 mixed into clear liquids like Gatorade.
PEG-4000 (used in China) and PEG-3350 (used in Europe and USA) are probably similar but
no studies have compared the 2 in humans.
Reference 1 - Integrated Analysis of Colorectal Cancer Reveals Cross-Cohort Gut Microbial
Signatures and Associated Serum Metabolites. Gastroenterology.  does not seem like an
appropriate choice for this fact.
My understanding is that colon/rectal cancer is the #2 cancer killer in the USA.
https://www.cancer.org/content/dam/cancer-org/research/cancer-facts-and-statistics/annual-
cancer-facts-and-figures/2023/2023-cancer-facts-and-figures.pdf
"duration of medicine" needs to be clarified
"volumetric laxative" do you mean osmotic laxative?
"this regimen is overdosed " needs to be better clarified
"The domestic guidelines" you need to say China
"has been gradually applied to our clinical population." I wold remove this or better clarify it.
"mechanism that effectively removes bowel fecal sludge and gas bubbles, achieving excellent
bowel preparation and causing fewer gastrointestinal reactions (11)" I would state that duel
mechanism.
"A large number of studies have shown that PICO not only improves bowel cleansing but also
has better tolerability and palatability and a higher willingness to repeat by patients (12-15)"
you need to give the background data for both your regimins, both in China and elsewhere.
"As people become more health-conscious, more and more young people are choosing
colonoscopy for screening, they place a higher value on taste and comfort, and therefore are
increasingly seeking low volume bowel cleansing solutions that taste good. At present, the main
low-volume bowel cleansing regimen commonly used in clinical practice are 2L PEG regimen
and PICO regimen. " I would remove this
Give the data for adequately cleansed colons.
The "real-world" [paragraph is not needed. You are doing a prospective, observational study
which is the more technical description of what I believe your mean by "real-world".
The background is too long and need to focus more on the past studies with 2 L PEG-ELS  and
PICO. You can comment that on the other low-lvolume preps that are not used in China.  It is
much improved from the first version.
METHODS
"To enhance the accuracy and safety of the examination, they should opt "  should be "They
were instructed to consume"
"was taken up to four hours before the procedure" - this needs to be netter defined - do you mean
4 hours before? why up to?
how much Dimethyl silicone oil ?
"Each box contained three packets: A ... B... C..."your description is ambiguous. Are there 3A
+ 3B + 3C? Are there 3 packets A+B+C?
I would use PEG-ELS throughout not PEG
"dissolving PEG 4000 and electrolyte powder " you mean dissolving all 9 or all 3 packets?
"All patients will be asked to complete a questionnaire before and after the colonoscopy,
with informed consent obtained prior to participation" you need to way when, at the time of
enrollment, just before the procedure was performed? 1 hour after the procedure?
A copy of the questionarre would be good (translated into English) or a description of what you
are asking with these questions. How do you judge compliance?
.It seems to me that "The post-procedure assessment will include whether the patient would
choose the same bowel preparation method again." would have been better asked before the
patients were sedated, but too late now to chance it.
"Before we started this data collection, we trained each endoscopist on BBPS. " how?
". A total BBPS score of #6, with three segments scoring #2 " you do not need to say total score
#6 since it must be #6 if all 3 segments are 2 or 3.
"About patient compliance, we judged whether patients were taking purgatives correctly as
required, whether they were following a low-residue diet requirements before the colonoscopy
and whether they were taking dimethyl silicone oil as required." How?
Overall Methods are much improved.
RESULTS
"The polyp detection rates were 42.2% and 45.5% (P=0.096), respectively. "  you need not
statistically significantly .
"To further investigate factors affecting sleep in the PICO group, we conducted univariate and
multivariate analyses. In the insomnia group, there were higher proportions of females, patients
experiencing nausea, abdominal discomfort, and those with a longer time to first defecation
(10.5% vs. 4.1%, P=0.001; 7.7% vs. 2.7%, P=0.002; 35.4% vs. 23.8%, P=0.006)#as shown in
Table 4. Multivariate analysis identified female gender, nausea, and abdominal discomfort as
significant factors impacting sleep (OR 1.473, 95% CI 1.019-2.130, P=0.040; OR 2.304, 95%
CI 1.160-4.576, P=0.017; OR 3.134, 95% CI 1.451-6.766, P=0.004), as shown in Table 5." I
would eliminate all this data. You are doing a detailed  analysis on a minor secondary endpoint
of the study. If this was on the primary endpoint, then it might be more appropriate. The editor
can comment on this.
Overall, Results much improved.
Discussion
I would get rid of "real-world"
". The results demonstrated that both PICO and 2L PEG achieved an adequate bowel cleansing
rate exceeding 90%. " you need statistical significance when describing your primary endpoint
and I would use the actual data not >90%/
"At present, low-volume bowel cleansing regimens mainly include 1-2L PEG plus adjuvate,
PICO, oral sulfate solution, etc.(23)" - not sure what you are saying here and not sure why there
is an "etc.". List them and if appropriate comment which ones are not used in China.
[comments in square brackets]
" Studies [what kind] have shown that PICO is comparable to 2L PEG/Bisacodyl in the cleaning
efficacy [how good?], but may be better in tolerability and acceptance(17, 24). In addition,
studies have shown that PICO showed a better trend in the cleansing of right colon compared
with 2L PEG/Asc and the rate of total adverse events significantly lower than 2L PEG/Asc
(47.4% vs. 62.4%, P = 0.031), indicating better tolerability and safety (25). Actually, the 2L
PEG regimen alone has been demonstrated to achieve an adequate rate of bowel preparation
in our previous studies (26), which is reach 91.6%. Although Europe and the United States (7)
recommend high-dose 4L PEG regimen for good bowel cleansing effect, several randomized
controlled studies and prospective, multicenter observational studies have shown that the bowel
preparation effect of 2LPEG is not inferior to 4L PEG (27-29) [what kind of numbers for
adequate cleansing are you seeing in these studies]. Moreover, in the 2023 expert consensus
on bowel preparation for colonoscopy released in China (30), 2L PEG is still used as an
alternative bowel preparation regimen, and the 2L PEG is also widely used in China. However,
a comparative study of these two low-volume bowel cleansing regimens (PICO and 2L PEG),
which are widely used in China, is lacking. Thus, in this study we compared the bowel cleansing
efficacy between these two regimens, and found a similar acceptable bowel cleaning efficacy,
which added to our understanding of the efficacy of 2L PEG and PICO in Chinese patients." -
most of this belongs in background.
"Previous randomized controlled trials for low-volume bowel preparation were mostly based on
low-risk populations with inadequate bowel preparation (26, 27). " - don't understand this.
I am confused by all the discussion of risk factors for inadequate preps when you do not report
your own data.
I would get rid of most of this. The discussion needs to be more focused and much shorter.
From Table 6, it appears that h/o abdominal surgery was the only "risk factor for suboptimal
preps" seen with any frequency in your study. There were too few patients with DM to say much.
You do not provide an analysis of the low-risk vs. higher-risk patients. I would combine add 2
columns to Table 6 showing all  segments >=2 and total BBPS along with P values.
Then you can talk a little about this. Most of this does not belong in the discussion.
"In this study, the adequate bowel cleaning rate reached 91%, " why did your study only reach
91%. What might you do in future studies to improve your rate?
"However, as a 'real-world' study, it may better reflect clinical reality than randomized controlled
trials. " randomized controlled prospective trials remain the gold standard. There is no reason
that your population could not be enrolled in one. We get about 95% of our patients to agree to
be subjects for studies of bowel prep regimens.
Your conclusion needs to use statistically significant
Your paper is much improved and headed the right direction. You need to focus the background
section on previous preps especially those you are using. You need to focus the discussion on
your primary and major secondary endpoints and how they compare to the literature.
I have provided suggestions on what needs to be eliminated to make the paper more focused on
your primary and major secondary endpoints.