The Renal Safety of Bowel Preparation With Polyethylene Glycol for Colonoscopy: A Prospective Cohort Study
Phase: NA
Conditions: Acute Kidney Injury
Sponsor: Evergreen General Hospital, Taiwan

1 
 
Title: Renal safety of bowel preparation with polyethylene glycol for outpatient 
colonoscopy: an observational prospective study 
Clinical trial registration name and number: NCT02657564 
Date: 11/18/2015 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

2 
 
Study Protocol 
  Colonoscopy has been shown to decrease CRC incidence and mortality by the 
removal of adenomatous polyps. Bowel cleansing is imperative procedure for 
colonoscopy examination. Oral sodium phosphate and polyethylene glycol (PEG) are 
the most frequently used bowel purgatives. Oral sodium phosphate preparations are 
hyperosmotic and promote colonic evacuation by drawing large volumes of water 
into the colon (1-1.8 L of water per 45 ml of preparation). Oral sodium phosphate 
preparations are associated with electrolyte imbalance as well as acute phosphate 
nephropathy, and the latter could be irreversible, requiring dialysis in some cases. 
The United States FDA warned that over-the-counter oral sodium phosphate 
products should not be used for colonoscopy bowel preparation which had led to the 
manufacturer to withdraw from the United States market.  
Currently, polyethylene glycol (PEG) solutions have become the most commonly 
used preparations for colon cleansing and their renal safety has been shown to be 
better than that of the sodium phosphate [8,11]. PEGs are non-absorbable isosmotic 
solutions that pass through the bowel without net absorption or secretion. 
Significant fluid and electrolyte shifts are therefore attenuated. There is no boxed 
warning regarding PEG use. PEG preparations can be used in patients with renal 
function impairment, congestive heart failure, or liver cirrhosis. However, several 
studies have shown that PEG and oral sodium phosphate share comparable renal 
safety profile. In addition, one recent population-based study reported that the use 
of PEG was associated with an increased risk of acute kidney injury (AKI).  
The primary aim of this clinical trial is to investigate the incidence and reversibility 
of AKI among adult patients undergoing colonoscopy with 3-L PEG preparation. The 
secondary study aim is to evaluate the incidence and severity of electrolyte 
disturbance with 3-L PEG bowel preparation. 

3 
 
METHODS 
Patients 
  This prospective, investigator-initiated clinical trial will be conducted at Evergreen 
General Hospital since January 2016. Subjects 40 yrs of age or older scheduled for 
elective colonoscopy, competent to provide written informed consent, and able to 
communicate effectively with study personnel are eligible for participation in the 
study.  
  Patients are considered ineligible for study participation if any of the following 
were present: severely reduced kidney function (an estimated glomerular filtration 
rate [GFR] <30 mL/min/1.73 m2); serum electrolyte abnormalities at screening; 
uncontrolled congestive heart failure (American Heart Association Classification III or 
IV); unstable angina; untreated dysrhythmia; current use of digitalis preparations or 
medications known to prolong QT interval; myocardial infarction, percutaneous 
transluminal coronary angioplasty, or coronary artery bypass graft surgery within the 
previous 3 months; ascites; current acute exacerbation of chronic inflammatory 
bowel disease; toxic colitis or toxic megacolon; ileus and/or acute obstruction or 
perforation; ileostomy, right or transverse colostomy, subtotal colectomy with 
ileosigmoidostomy and/or ≥50% of colon removed; idiopathic pseudo-obstruction; 
history of gastric stapling or bypass procedure; difficulties swallowing; treatment 
with an investigational drug or product; participation in a drug study within 30 days 
prior to receiving study medication; treatment with another bowel preparation 
within 21 days prior to colonoscopy; known allergy or hypersensitivity to PEG 
solution; or any other clinically significant disease or finding that, in the opinion of 
the investigator, would expose the patient to an increased risk of significant adverse 
event or would interfere with the assessments of the safety during the course of 
treatment. 

4 
 
PEG Preparations and Colonoscopy Sedation 
A split-dose of the bowel preparation with PEG is provided for morning 
colonoscopy and a same-day preparation is provided for afternoon colonoscopy. 
Three sachets of PEG dissolved in 3 L of water are used for colon preparation. After 
completion of PEG ingestion, additional clear liquids are allowed as desired until 2 
hours before the schedule time of the colonoscopy. Moderate conscious sedation 
with fentanyl and midazolam is provided for all endoscopic procedures.  
Participant Flow and Follow-up 
Screening visit (up to 28 days before colonoscopy; Visit 1) 
  The following will be obtained or performed at the screening visit: written 
informed consent, complete medical history, physical examination, vital sign 
measurements, information regarding concomitant medications received in the past 
7 days, information regarding contrast media exposure in the past 3 months, and 
blood specimen for serum chemistry analysis. A urine pregnancy test will be 
performed for women of childbearing potential. Patients receive 3 sachets of PEG 
and are instructed to consume the PEG preparations according to their colonoscopy 
schedule by study personnel. Each patient is provided with written dietary and PEG 
instructions.  
Colonoscopy (Visit 2) 
  Immediately before colonoscopy and before each patient is sedated, study staff 
perform or obtain patient medical history, complete physical examination, vital sign 
measurements, information regarding concomitant medications received since the 
screening visit, and specimens for serum chemistry analysis. Patient will complete a 
questionnaire concerning their experience with PEG on 5-point Likert scale (1 = 
severely distressing, 2 = distressing, 3 = bothersome, 4 = mild, and 5 = no symptoms). 
Compliance is assessed by measuring the volume of PEG solution remaining. 

5 
 
  Immediately following the colonoscopy, the investigators assign a score for the 
overall quality of colon cleansing using Boston bowel preparation scale (BBPS). An 
excellent bowel preparation is defined as a total BBPS score of 8 or higher, a good 
preparation as a total score of 7, a fair preparation as a total score of 6, and a poor 
preparation as a total score of 5 or less. 
Follow-up (up to 28 days after colonoscopy; Visit 3) 
The following will be obtained or performed at the follow-up visit: physical 
examination, vital sign measurements, information regarding concomitant 
medications received after colonoscopy, and blood specimen for serum chemistry 
analysis.  
Data Analysis and Definition 
The serum creatinine level on visit 1 is recorded as the baseline renal function. 
Parameters used for assessing the renal function are change in serum creatinine 
value (differences between visit 2 and visit 3 from baseline serum creatinine levels) 
and per cent change in creatinine value (the percentage change of serum creatinine 
compared to baseline value). AKI is defined as ≥50% increase in baseline serum 
creatinine. The proportion of patients with ≥25% increase above their baseline 
creatinine level will also be identified. In addition, We will compare the change in the 
estimated GFR (differences between visit 2 and visit 3 from baseline GFR value). The 
GFR is estimated using the Modification of Diet in Renal Disease Study Group (MDRD) 
formula. Assessment of changes in serum electrolyte values (including calcium, 
phosphate, chloride, magnesium, sodium, potassium) between visit 2 and visit 3 
from baseline values are also performed. The incidences of electrolyte disturbance 
will be evaluated.