Introduction of bowel preparation (BP) and Polyethylene glycol (PEG)

Colonoscopy is useful for screening colorectal cancer and has contributed to decreasing its incidence and mortality. Its efficacy and safety correlate with adequate bowel preparation (BP), leading to higher adenoma detection rates (ADR) and lower risks of incomplete colonoscopy.

Polyethylene glycol (PEG) solution is usually used for colonoscopic BP. Traditionally, 4 L PEG was adopted for BP; however, a considerable number of patients found it difficult to complete BP, due to the large volume of lavage solution needed. Nowadays, 4 L PEG has been replaced by 2 L PEG-Asc in Japan and Europe. However, the volume of lavage solution still hinders patients' acceptability. Several studies, conducted to further reduce the dosage of 2 L PEG-Asc, have reported the use of adjunctive agents to reduce the volume of PEG-Asc solution required to 1 L, thereby improving patient acceptability.

clinical research

Low-volume polyethylene glycol plus ascorbic acid (PEG-Asc) reduces the dosage of colonoscopic bowel preparation (BP) solution, but is still poorly tolerated. Adding laxatives to the BP solution reduces the volume of fluid required, without affecting quality.

A single-center, randomized, investigator-blinded, noninferiority trial was performed between June and August 2022. Outpatients scheduled for colonoscopy were randomized (1:1) to the 1L-PEG/AS or 2L-PEG/A group. The Boston Bowel Preparation Scale (BBPS) was used to evaluate BP quality. Adverse events and tolerability were surveyed using questionnaires.

Overall, 344 patients received 1L-PEG/AS or 2L-PEG/A regimens. The baseline characteristics and adverse events of the two groups were comparable. The 1L-PEG/AS group showed noninferior adequate BP rates compared with the 2L-PEG/A group (88% vs. 89%, P = 1.00); overall BBPS was 7.1 ±1.5 and 7.2 ± 1.5, respectively (P = 0.39). Higher willingness to repeat the BP was observed in the 1L-PEG/AS group (85% vs. 62%, P < 0.01).

The 1L-PEG/AS regimen was comparable to the 2L-PEG/A regimen in terms of BP adequacy, requiring lower BP solution volumes, with better patient tolerance. Thus, it may be a suitable alternative to the conventional BP solution for colonoscopy.

Patient compliance, adverse events, and tolerability

Presents patient compliance: No significant differences were found regarding compliance with purgatives (P = 0.13) or dietary instructions (P = 0.57) between two groups. Both groups received colonoscopy within 6 h after the intake of PEG-Asc solutions. However, more patients in the 2L-PEG/A group took<80% of solution compared to those in the 1L-PEG/AS group (17% vs. 3%, RR 0.17, 95% CI 0.07–0.42, P < 0.01). Patients in the 1L-PEG/AS group drank more additional clear liquid than those in the 2L-PEG/ A group (0.6 ± 0.4 L vs. 0.3 ± 0.2 L, P < 0.01).

Presents adverse events: Nausea, vomiting, abdominal pain and discomfort, and quality of sleep, were comparable between the two groups. No patients experienced moderate-to-severe abdominal pain or ischemic colitis.

Presents tolerability: More patients in the 1L-PEG/AS group were willing to repeat the BP than those in the 2L-PEG/A group (85% vs. 62%, RR 1.36, 95% CI 1.19– 1.57, P < 0.01), and this trend was observed regardless of prior history of colonoscopy. More patients in the 2L-PEG/A group were unwilling to repeat BP than those in the 1L-PEG/AS group due to larger volumes of PEG-Asc consumed (49% vs. 18%, RR 0.37, 95% CI 0.26–0.52, P < 0.01).

References:

[1] MAEDA NATSUMI. EFFICACY AND TOLERABILITY OF 1-L POLYETHYLENE GLYCOL PLUS ASCORBIC ACID WITH SENNA VERSUS 2-L POLYETHYLENE GLYCOL PLUS ASCORBIC ACID FOR COLONOSCOPIC BOWEL PREPARATION: A PROSPECTIVE, RANDOMIZED, INVESTIGATOR-BLINDED TRIAL[J]. Gastrointestinal endoscopy, 2023. DOI:10.1016/j.gie.2023.04.552.