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: 1 Date: 02 Nov 2024
Reviewer's report:
TITLE - needs to describe the type of study (prospective, retrospective, randomized, etc.). PEG
is likely PEG-ELS.
ABSTRACT [comments before reading the paper]
methods needs to describe the type of study.
Adequate prep needs to be defined (all segments 2 or 3).
adverse reactions, pt compliance as measured how?
"based on the bowel preparation regimen used" this could be better clarified.
2 L PEG needs to be better described..
Is it PEG-4000? PEG-3350?
Are there electrolytes?
You should say there were no statistically significant differences between the groups in ...
"total colon and right colon cleansing were more effective in the PICO group compared to the 2L
PEG group [(6.90 ± 1.19) vs. (6.81 ± 1.14), P=0.016; (2.15 ± 0.53) vs. (2.11 ± 0.51), P=0.005].
You ned to use the term statistically significant differences
BACKGROUND
"method of first choice for screening" should be rephrased.
"and a missed adenoma detection rate of up to 47.9% " this is not correct since the adenoma
detection rate is rarely 47%. Do you  intend to say that up to 47% of adenomas may be missed?
4L PEG-ELS (not PEG) is a recommended bowel cleaning regimen but up to 33% of patients
can not finish it.
While it is true that the "majority" of patients can be cleaned with 2 l PEG-EPS, our goal is
to adequately cleanse close to 100% of patients not 51%. Yo uneed to go on and discuss the
studies with 2 L PEG-ELS and their poor results (typically 80%). 2L PEG-ELS is no longer
sold in the USA.
You need to describe what PICO is. What is in it? How does it work?
In the USA, it is sold as a solution to powder as 10mg/3.5g/12g per 16.1 g of powder (available
as carton containing two 16.1 g packets of powder). You need to state what you are using and
what it contains. It is always nice to compare the 2 regimins side by side for content and total
osmoles. You also need to state you are giving it as a split dose.
The stimulant laxative activity of sodium picosulfate together with the osmotic laxative activity
of magnesium citrate produces a purgative effect which, when ingested with additional fluids,
produces watery diarrheaSodium picosulfate, a prodrug, is converted to its active metabolite,
bis-(p-hydroxy-phenyl)-pyridyl-2-methane (BHPM), by colonic bacteria
Magnesium oxide and citric acid react in water to create magnesium citrate.
Is Dimethyl silicone part of your regimin? If so it needs to be described.
You need to describe the data using PICO (ranges of adequate preparations or Boston Total
scores) and give more details of any studies comparing PICO and 2 L PEG/
METHODS
Was the trial registered (in China or USA) with a site such as https://clinicaltrials.gov/?
Any power calculation?
Prospective observational or retrospective?
Why were patients excluded if the scope did not reach the cecum? If the prep was poor and
prevented the advancement of the scope then this should be counted as a failed prep. If there
were technical issues advancing the scope, then the segments seen sduld be graded.
You need to better describe the diet/ Where they able to eat dinner the day prior? Did they jeat
a low finer diet all day long?
2L PEG  is 2 L PEG-4000 with electrolytes given as a split dose. Are all 3 packets dissolved
into 1000 ml of water? How much was taken the day-prior? How much was taken the morning
of the procedure?
"All patients will be asked to complete a questionnaire before and after the procedure, with
informed consent obtained prior to participation" When before and when after?
Did the endoscopists get trained to use the BBPS?
"The bowel cleansing effect was rated on a scale from 0 to 3, with 0 indicating poor and 3
indicating good preparation" is not the definition of the BBPS and you need to list the correct
definition in the text or in a table. What definition did your endoscopists use?
". A total BBPS score of #6, with each segment scoring #2, was considered indicative of adequate
bowel preparation."
That is repetitive. You only need to state that each segment had a score or 2 or 3 (>=2).
"The bowel cleansing air bubble score was categorized into four levels: <5%, 5%-25%,
25%-50%, and >50%. " I have never heard of this before. Is there any validation or
standardization to this scale?
What is Dimethyl silicone oil? Why was it used? Why did only 90% of patients use it (Table 1)?
RESULTS
"groups were 48.90 ± 13.74 and 53.02 ± 14.27, respectively (P=0.000), " - this needs to be
P<0.001 or something similar, not 0).
"The mean ages of the PICO and 2L PEG groups were 48.90 ± 13.74 and 53.02 ± 14.27,
respectively (P=0.000), indicating a higher proportion of younger patients opting for the PICO
regimen" - you need to use the term statistically significant (as you did in the next sentence) .
"However, the 2L PEG group had a higher proportion of diabetic patients (4.6% vs. 2.2%,
P=0.002), while the PICO group had more patients with a history of abdominal surgery (31.9%
vs. 20.7%, P=0.000), as shown in Table 1." - you need to use the term statistically significant.
"Table 2 shows that both the PICO and 2L PEG groups achieved high rates of adequate bowel
cleansing, with 92.2% and 91.3%, respectively (P=0.437). " - you need to use statistically
significant - for example, "There was no statistically significant difference in adequate bowel
preparations as measured by the BBPS between the PICO and 2L PEG groups (stats here)."
If you wish to comment on the "high" rates of cleanliness that is fine after but you then need
to give perspective and compare this to other authors and other regimins. Some can approach
99% which is far better than your data. Most of these use clear liquids (for some or all of the
day before) and do not feed their patients dinner when cleaning them out.
I am not sure the bowel bubble score needs to be reported since this is not a standard part of
bowel prep scales and your study did not find any difference. Let me know why you are reporting
it and how this compares to others using such a scale.
What is "sleep disturbance"? Does that mean they had to get up in the middle of the night to
have a bowel movement?
I am not sure "we conducted univariate and multivariate analyses" is appropriate for this but
describe to me what you are doing here.
DISCUSSION
You need to start by describing the study (Prospective or not, observation or randomized) and
the primary data point (BBPS all segments 2 or 3). You can then comment on that data point
and compare it to the literature, especially other studies of PICO and 2 L PEG-ELS.
"The proportion of low-risk individuals in the PICO and 2L PEG groups was 46% and 45%,
respectively" Where does this data come from? You need to present it in your tables and results
to discuss it here.
Your discussion spends too much time discussing risk factors for suboptimal preps and side
effects of 2 regimens that were quite similar. That was not the primary data point of your study
and needs top be cut way back.
You need to discuss how your results compare to the literature and other low-volume regimens.
Sulfate solution, PEG-3350 without electrolytes (commonly used in the USA), Polyethylene
glycol 3350 + ascorbic acid. Are these used in China?
2 liter PEG-ELS was removed from the market in the USA, partially due to poor cleansing
results that often were close to 80% in the published literature.
You need to discuss how you can improve your results from 90% to 99%. Should you have fed
them dinner? Do they need higher volumes of PEG? Is compliance an issue with the regimens?
For example, in my center, we would not be satisfied with 90% adequately cleansed colons. Our
results approach 99%, mostly using pure PEG-3350 (306 g),  sulfate solution and Sulfate tablet
preparations. We always use clear liquids the day prior but I know that the literature is mixed
on this. There is not much literature about feeding patients dinner and expecting a good split
prep result. You need to discuss this.
Among Your limitations
1) Not randomized.
2) groups not matched by age.
3) was this prospectively obtained data?
4) Fed them dinner
All your comparisons need to use the terms "statistically significant"
TABLE 1
The first line of data below the header should be n (not shown in the header).
P values should not be 0.
Gender is repetitive. Just use Male Gender (Female is 1-male).
Reasons for colonoscopy (n, %) - Indications is a better term
Medical chechup needs to be defined. Screenign average risk patients? Screening high risk
patients with a FH?
Whatg is recheck? Do they have a history of polyps or cancer?
What is Symptom? Define this or split it up into smaller groups (rectal bleeding, anemia, etc.).
Why is Dimethyl silicone use not 100%?
"Risk factors of bowel preparation" - not sure what you mean? Risk factors for suboptimal prep?
TABLE 2
n should be the first line in the table
"Adequate bowel cleansing rate (n, %)" needs to be BBPS all 3 segments 2 or 3
Polyp detection rate (n, %) goes below BBPS data which should be listed on consecutive lines.
Bowel Preparation completion rate needs to be better broken down. There is a huge difference
between 100% and 75%. 100% (or 95-100%) should have its own line.
P values are <0.0001 etc, not 0
TABLE 3
P cant be 0