\# Sample Size Calculation: This clinical study aims to demonstrate that the experimental group (early feeding group, P1) is not clinically inferior to the control group (delayed feeding group, P2) in patients undergoing colorectal endoscopic submucosal dissection (ESD). The primary efficacy endpoint is set as the incidence rate of early complications within 24 hours post-procedure. For non-inferiority testing, the incidence of early complications (P1 = P2) was assumed to be 3%. The non-inferiority margin (D) was set at 8%, with a significance level (alpha) of 2.5%, power of 80%, and a 1:1 allocation ratio. Using the PASS software (version 11), the calculated sample size was 74 patients per group. Considering a dropout rate of 5%, the required sample size is 78 patients per group, totaling 156 participants.
\# Randomization and Blinding: This clinical study employs block randomization to allocate participants to the experimental group (early feeding) and the control group (delayed feeding) in a 1:1 ratio. Blinding will not be applied. A randomization table will be generated independently by a statistician from the Medical Statistics Department of Pusan National University Hospital, using the blockrand package in R (version 4.3.3; R Core Team, 2024, http://cran.r-project.org). The block size will remain blinded.
\# Research Participation Procedure: After signing the consent form, the admission process is initiated. Basic tests such as blood tests, ECG, and chest/abdominal X-rays are conducted. Fasting and bowel preparation are performed the day before the procedure.
\# Procedure and Initial Management: On the day of the procedure, both groups undergo standard colorectal ESD. Two hours after the procedure, a physical examination, CBC, and chest/abdominal X-rays are performed.
\# Dietary Group Classification: Early Feeding Group: If no abnormalities are found during the examination 2 hours after the procedure, water intake begins, followed by a liquid diet and then a porridge diet if no complications occur.
Late Feeding Group: Patients remain fasting on the day of the procedure. A liquid diet begins 24 hours after the procedure, followed by a porridge diet if no complications occur.
\# Survey: Patient satisfaction is evaluated through a survey. Patients visit the outpatient clinic after discharge to review procedural outcomes and assess for delayed complications.
\# Observation Items: Age, sex, height, weight, BMI, underlying diseases (hypertension, diabetes, cerebrovascular disease, ischemic heart disease, other heart diseases, atrial fibrillation (or atrial flutter), other arrhythmias, chronic kidney disease, dialysis status, liver cirrhosis, other vascular diseases), history of previous abdominal surgery, smoking history, alcohol consumption history, medication history (aspirin, clopidogrel, other antithrombotic agents, warfarin, direct oral anticoagulants (DOACs), nonsteroidal anti-inflammatory drugs (NSAIDs), steroids), type of bowel preparation used, pre-procedure serum white blood cell count, pre-procedure serum hemoglobin, pre-procedure serum platelet count, pre-procedure absolute neutrophil count, pre-procedure prothrombin time (PT) (including INR), pre-procedure activated partial thromboplastin time (aPTT), post-procedure serum white blood cell count, post-procedure serum hemoglobin, post-procedure serum platelet count, post-procedure absolute neutrophil count, location of the lesion, size of the lesion (long axis, short axis), macroscopic morphology of the lesion, degree of submucosal fibrosis, resection method, resection time, post-resection management time, total procedure time, type of post-resection management performed, en bloc resection status, occurrence of complications during the procedure, measures taken for intra-procedural complications and their outcomes, occurrence of complications within 24 hours post-procedure, measures taken for complications within 24 hours post-procedure and their outcomes, occurrence of complications beyond 24 hours post-procedure, measures taken for complications beyond 24 hours post-procedure and their outcomes, length of hospital stay (days), pathology results (histology, differentiation grade, invasion depth, horizontal resection margin, vertical resection margin, lymphatic invasion, vascular invasion, perineural invasion), number of days until outpatient follow-up after discharge, patient satisfaction (Likert scale).
\# Data Analysis and Statistical Methods: Descriptive statistics will be used to summarize the data: continuous variables will be presented as the number of observations, mean, standard deviation, minimum, maximum, and quartiles, while categorical variables will be presented as frequencies and percentages. Group comparisons will be conducted using an independent t-test or Wilcoxon rank-sum test for continuous variables and a chi-square test or Fisher's exact test for categorical variables. To confirm the non-inferiority of the treatment group (T) compared to the control group (C), the two-sided 95% confidence interval for the difference in proportions (T-C) will be calculated. Non-inferiority will be established if the upper limit of the confidence interval is within the predefined non-inferiority margin. A two-sided test will be performed at a significance level of 5%. No interim analysis will be conducted in this clinical study, and no imputation methods for missing data will be applied.
