Review Reports

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Dear colleague,
congratulations on the work done.
Conducting a multicenter study, even a retrospective one, of patients with ulcerative colitis is a complex task.

It is a methodologically sound study that addresses an important problem in these patients.

I have some questions and suggestions:

- The study mentions the good preparation of patients using the Boston Diagnostic Scale, but it doesn't mention the diagnoses made. Do we know in how many colonoscopies lesions were found?

- Were the patients asymptomatic in any case?

- I believe the lack of information on the patients' concomitant medications is a significant limitation, and this should be explicitly addressed in the limitations section.

Congratulations

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

This multicenter retrospective study in UC patients in remission addresses a clinically relevant question and reports high overall bowel-prep adequacy, with higher BBPS scores and completion rates in the 1L-PEG-ASC group. However, some issues must be addressed:

1. BBPS is operator-scored, and inter-endoscopist/inter-center variability can bias comparisons, especially when differences are modest. Were endoscopists blinded to the bowel-prep regimen? Was BBPS scoring standardized or calibrated across centers?
2. You excluded patients who did not complete colonoscopy due to “intolerance” or “high risk of perforation.” Were these exclusions applied before BBPS was assessed? Please clarify whether incomplete procedures contributed BBPS values and how they were handled analytically.
3. The exclusion criterion uses MES ≥1 and UCEIS >2. This implies MES=0 only, but UCEIS ≤2 may still allow mild endoscopic activity. Could you clarify and harmonize the remission definition across scoring systems and confirm how remission was operationalized at each center?
4. Beyond excluding prior ileal/colonic surgery, ostomy, or PEG-J, were other established predictors of inadequate bowel preparation assessed or excluded (e.g., constipation, diabetes, opioid use, neurologic disease)? If these variables were not collected, please acknowledge potential residual confounding.
5. Please add a STROBE-style flow diagram showing the number of patients screened, excluded (with reasons), and included in the final analysis, stratified by bowel-prep regimen.
6. Because timing and diet strongly influence BBPS, please provide detailed protocol information: split-dose schedule (evening/morning), timing relative to colonoscopy start time, dietary restrictions, and whether these instructions were standardized across centers and consistent between regimens.
7. The manuscript concludes that “traditional risk factors were not predictive,” but only 36 patients had inadequate preparation. With this event count, multivariable modeling may be underpowered and prone to false-negative findings. Please discuss event-per-variable limitations, and note that several key predictors (constipation, diabetes, opioid use, prior inadequate preparation, adherence) were not available.
8. You modeled total BBPS using ordinal logistic regression adjusted for age, sex, and maximal disease extension. Please justify why an ordinal model was selected over linear modeling or alternative approaches, and report assessment of the proportional odds assumption (Brant test).
9. The 2L group pools Moviprep and Clensia, which differ in formulation and may differ in performance and tolerability. Please conduct a sensitivity analysis separating Moviprep vs Clensia, or adjust for product type within the 2L group, to confirm that the main findings are not driven by within-group heterogeneity.

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

Thank you for your responses. I have reviewed these and find them appropriate; therefore, I have no further comments.