Conditions: Unrecognized Condition
Allocation: RANDOMIZED | Intervention model: PARALLEL
Enrollment: 352
Healthy volunteers: yes

Brief summary:
Split dose bowel cleansing is recommended method for colonoscopy. For afternoon colonoscopy, same-day dose of bowel cleansing is alternative option. Recently, same-day bowel cleansing for morning colonoscopy was validated. To date, there was no study which compared the bowel cleansing efficacy between same-day dose and split dose regardless of colonoscopy time. The aim of current study is to compare the bowel cleansing efficacy, adverse events, and patient's tolerability between the two group.

Subjects who underwent colonoscopy for various reasons were included. After agreeing to participate in the study, study participants were randomly assigned to split dose or same day dose group. Bowel cleansing is done using polyethylene glycol (PEG). All colonoscopy was done between 10 AM to 6 PM. Study participants were instructed to ingest 500ml PEG every 15 minutes. Subjects who were assigned to split dose group ingested 2L PEG from 9PM 1 day before colonoscopy. Remaining 2L PEG was ingested 3-5 hours before colonoscopy. In the same-day dose group, bowel cleansing was started from 5AM for subjects who were scheduled to receive colonoscopy in the morning. Afternoon colonoscopy group in the same-day dose group ingested 2L PEG from 5AM. Remaining 2L PEG was finished 3-5 hours before colonoscopy.

Bowel cleansing efficacy was assessed using Boston bowel preparation scale. Vital signs and laboratory tests were checked before colonoscopy. Study participants completed questionnaire which contained patient's satisfaction, tolerability, and adverse event during bowel cleansing. Bowel cleansing efficacy, patient's tolerability, and safety profile were compared between the two groups. Successful bowel cleansing was estimated 85% for split dose group.

The investigators set 10% for inferior margin. Considering 10% drop out, a total of 352 subjects will be recruited.

Detailed description:
Randomization and blinding:

Randomization will be done using computer generated randomization list. A specialized nurse will explain the method of bowel cleansing. Investigators (endoscopists) are blinded to bowel cleansing method.

Endpoint:

Primary end point is successful bowel cleansing rated by Boston bowel preparation (BBPS) scale. Successful bowel cleansing is defined as all segment is 2 or 3 points. Endoscopists will assess BBPS when colonoscopy withdrawal.

Secondary end point was patient's tolerability and safety profile including adverse events. Patient's satisfaction to the different bowel cleansing method and adverse events (nausea, vomiting, dizziness, fatigue) will be investigated by questionnaire before colonoscopy. Blood test will be done before colonoscopy.

Statistical analysis:

Bowel cleansing success, patient's tolerability and safety profile will be compared between the two groups. Student t test for continuous variables and the chi-square test or Fisher exact test for categorical variables.

Sample size:

This study is non-inferioty study. Assuming bowel cleansing success rate 85% in the split-dose group, the significant difference between the two groups were hypothesized at 10%. Considering 80% power and 10% drop rate, a total of 352 participants is needed.

Arms:
arm 1: Participants who ingest bowel cleanser on the day of colonoscopy. Participant will ingest the 4L PEG on the day of colonoscopy. arm 2: Participants who ingest bowel cleanser by split dose. 2L PEG will be ingested 1 day before colonoscopy. Remaining 2L bowel cleanser will be ingested on the day of colonoscopy.

Interventions: intervention 1: Polyethylene Glycol (PEG)
Intervention descriptions: intervention 1: Different method for bowel cleansing using same bowel cleanser. Same-day dose group : 4L PEG will be ingested on the day of colonoscopy Spli-dose group : 2L PEG will be ingested 1 day before colonoscopy, remaining 2L PEG will be ingested on the day of colonoscopy

Protocol document:
Prot_SAP_000.pdf: 
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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).