Bowel Preparation Efficacy and Safety of 1 L vs 2 L Polyethylene Glycol With Ascorbic Acid for Colonoscopy: A Randomized Controlled Trial

Polyethylene glycol with ascorbic acid (PEG/Asc) is a well-established bowel preparation solution with guaranteed effectiveness and safety. A new low-volume agent, 1 L-PEG/Asc, has recently been released. This study aimed to compare the bowel cleansing efficacy and safety of 1 L-PEG/Asc and 2 L-PEG/Asc administered to adult outpatients in a split-dose manner. METHODS: Outpatients undergoing colonoscopy enrolled in a single-blinded, single-center, noninferiority study conducted between July and October 2021 were randomized in a 1:1 manner to a 1 L-PEG/Asc or 2 L-PEG/Asc group. Bowel cleansing was assessed using the Boston Bowel Preparation Scale (BBPS) and the Harefield Cleansing Scale in intention-to-treat and per-protocol populations. RESULTS: Two hundred forty participants were randomized and allocated, with 120 patients in the 1 L and 2 L-PEG/Asc groups, respectively. Noninferiority was demonstrated for overall successful bowel cleansing (BBPS: 92.5% vs 90.8%; 95% confidence interval [CI], −0.054 to 0.087) and the high-quality cleansing rate of the right-sided colon (BBPS = 3, 40.0% vs 35.8%; 95% CI, −0.082 to 0.165; Harefield Cleansing Scale ≥3, 50.0% vs 43.3%; 95% CI, −0.060 to 0.194) in the intention-to-treat population. The overall incidence of adverse events was similar in both groups ([82/120] 68.3% vs [72/120] 60.0%; P = 0.178). The tolerability, acceptability, and compliance rates of both regimens were similar, with no significant differences. DISCUSSION: Compared with 2 L-PEG/Asc, 1 L-PEG/Asc achieved successful overall bowel cleansing efficacy with high-quality cleansing in the proximal colon and proved its noninferiority. Therefore, 1 L-PEG/Asc is an acceptable alternative bowel cleansing solution.