Randomized trial of 2-L polyethylene glycol+ascorbic acid versus 4-L polyethylene glycol as bowel cleansing for colonoscopy in an optimal setting

Background and Aim: Prior studies have reported 2-L polyethylene glycol (PEG) plus ascorbic acid (PEG+Asc) is an effective alternative to standard 4-L PEG for bowel preparation before colonoscopy, but they are limited because of some confounders. Therefore, we compared the efficacy, patient compliance, satisfaction, and safety of 2-L PEG+Asc versus 4-L PEG for bowel cleansing in optimal preparation strategies. Methods: In this prospective, randomized, single-blind trial, consenting outpatients were randomly assigned to one of two arms. All colonoscopies were scheduled in the morning and cleansing solutions were administered as a split-dose regimen. Bowel-cleansing efficacy in three different segments was measured on a five-point scale with four-point overall grading. Patients' opinions of the preparation regimens were obtained by questionnaire. Results: There was no significant difference between the 2-L PEG+Asc (159/163; 97.5%) and 4-L PEG (162/164; 98.8%) with respect to the overall success of bowel cleansing (mean difference=-1.3 [-4.1-∞]). Patient compliance, acceptability, and satisfaction were better in the 2-L PEG+Asc arm than the 4-L PEG arm (P<0.05). Additionally, the incidence of side effects was lower in the 2-L PEG+Asc than the 4-L PEG (overall, 57.7% vs 73.2%, P<0.05). However, no significant difference was seen in patients' rating of taste. Conclusions: In an optimal preparation setting, 2-L PEG+Asc has equal efficacy as a bowel cleanser prior to colonoscopy as 4-L PEG, with the advantages of better patient compliance, satisfaction, and safety.