Comparison of Bowel Cleansing Efficacy Between Same-day Dose Versus Split Dose : A Single Center, Operator Blinded, Prospective Randomized Controlled Trial
Phase: PHASE3
Conditions: Unrecognized Condition
Sponsor: Incheon St.Mary's Hospital

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Comparison of bowel cleansing efficacy, safety, bowel movement kinetics, 
and patient tolerability of same-day and split-dose bowel preparation using 
4 L polyethylene glycol: a prospective randomized study 
 
Clinicaltrail.gov: NCT03315949 
 
Date: May 18, 2019 
 
 
 

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MATERIALS AND METHODS 
Study Population and Protocol 
This was a single-center, prospective, assessor-blinded, noninferiority, randomized controlled 
study conducted at a tertiary referral center (Incheon St. Mary’s Hospital, Incheon, Korea). 
Individuals who underwent colonoscopy with or without esophagogastroduodenoscopy 
(EGD) for various indications were eligible for inclusion. Study subjects were enrolled 
between November 2017 and February 2018. Individuals who met all of the following criteria 
were included: (1) age 40–75 years; (2) American Society of Anesthesiologists (ASA) class I 
or II; (3) outpatients; and (4) no previous history of bowel resection or gastrectomy. 
Exclusion criteria were as follows: (1) cancellation, (2) violation of protocol for bowel 
preparation, such as subjects in the SDD group ingesting a purgative the previous day or as 
an SPD; or subjects in the SPD group ingesting a purgative the previous day or as an SDD. 
After informed consent was obtained, study subjects were randomly assigned to the SDD or 
SPD group. Randomization was performed using a block size of four, stratified by 
colonoscopy time (morning vs afternoon) and sex, using a computer-generated randomization 
list. 
The protocol for bowel preparation is shown in Figure 1. Subjects underwent bowel 
preparation at home. Study subjects were encouraged to finish 2 L PEG within 1 h. If 
ingestion was difficult, 2 L PEG was consumed within 1.5 h. Hence, 2 to 3 h were required to 
fully ingest the 4 L PEG. Individuals in the SDD group ingested PEG on the day of the 
colonoscopy. For those who underwent morning colonoscopy, ingestion of 4 L PEG was 
started at 5 a.m. Individuals who were scheduled to undergo afternoon colonoscopy were 
instructed to take 2 L PEG starting at 7 a.m., then after a 2-h break, the remaining 2 L PEG 
was ingested starting at 10 a.m. Individuals in the SPD were instructed to begin ingesting 2 L 

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PEG at 9 p.m., 1 day before the colonoscopy. The remaining 2 L PEG was ingested from 7 
a.m. for morning colonoscopy or from 10 a.m. for afternoon colonoscopy. We encouraged the 
participants to ingest additional water until their bowel effluent was clear. Consumption of 
fibers and seeds was restricted for 2 days before colonoscopy. Soft food was allowed for 
dinner the day before colonoscopy. Colonoscopy was performed between 10 a.m. and 5 p.m. 
(morning colonoscopy 10 a.m.–12 p.m.; afternoon colonoscopy 1:30 p.m.–5 p.m.) by three 
board-certified colonoscopists with experience of more than 2000 cases. The colonoscopists 
were blinded to the bowel cleansing regimen. This study was approved by the Institutional 
Review Board of Incheon St. Mary’s Hospital and registered at ClinicalTrials.gov 
(NCT03315949). 
Bowel Cleansing Efficacy, Bowel Movement Kinetics, and Colonoscopy Results 
The primary endpoint of this study was the bowel cleansing efficacy assessed by the Boston 
bowel preparation scale (BBPS). The BBPS score is the sum of three segmental scores (range 
0–9).18 Each segment is graded on a 4-point scale: 0, inadequate; 1, poor; 2, good; and 3, 
excellent. The rates of cleansing success, defined as all segments 2 and total BBPS score, 
were compared between groups. The bowel cleansing efficacy was also assessed by the 
Aronchick scale, which has scores of excellent, good, fair, poor, and very poor; details of the 
Aronchick scale are described elsewhere.19,20 
Bowel movement kinetics included the number of defecations, the start and finish time 
of bowel preparation, and the last defecation time. The amount of PEG and additional water 
ingested were recorded. 
The results of the colonoscopy were analyzed. The cecal intubation time, colonoscopy 
withdrawal time, polyp detection rate (PDR), ADR, and the number of adenomas per patient 

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were recorded. For those who underwent EGD, fluid in the stomach was suctioned and its 
volume was measured. 
Safety and Tolerability 
The composite safety profile included vital signs and questionnaire findings. Vital signs were 
checked on the day of randomization and at colonoscopy. Before the colonoscopy, all study 
subjects completed a questionnaire asking about adverse events, tolerability, and bowel 
movement kinetics.17,20 The questionnaire contained the following items: (1) adverse events 
related to the ingestion of the purgative; (2) number of sleep disturbances during the night 
before colonoscopy; (3) overall satisfaction with the bowel cleansing regimen (very satisfied, 
satisfied, intermediate, dissatisfied, very dissatisfied); and (4) willingness to use the bowel 
preparation regimen again. The patients used a checklist of possible adverse events to report 
whether they had experienced any of the following during or after ingestion of the bowel 
cleanser: nausea, vomiting, bloating, abdominal pain, dizziness, headache, and/or any other 
symptoms. 
Statistical Analysis 
We assumed a bowel cleansing success rate for SPD of 85% and set the inferior margin at 
10%. With 80% power and a type I error of 0.05, the required sample size for each group was 
calculated to be 158. A total of 176 subjects in each group was required, considering a 10% 
drop-out rate. Continuous variables are expressed as mean ± standard deviation. Categorical 
variables are expressed as number and percent. The demographic characteristics, bowel 
cleansing efficacy, safety profile, tolerability, bowel movement kinetics, and results of 
colonoscopy were compared between the two groups. For this analysis, we used Student’s t 
test for continuous variables, and the chi-square or Fisher’s exact test for categorical 
variables. A p-value <0.05 was considered significant. The safety analysis of safety and 

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tolerability included all subjects except those who were excluded for cancellation or protocol 
violation. Per-protocol (PP) analysis was used for the patients who completed colonoscopy. 
Bowel cleansing efficacy and bowel movement kinetics were investigated in the PP analysis. 
All statistical analyses were conducted using SAS software (9.0; SAS Institute, Cary, NC, 
USA).