A Multicenter Randomized Controlled Trial Comparing Two Bowel Cleansing Regimens for Colonoscopy After Failed Bowel Preparation

Abstract

Background & aims: Failed bowel preparation for colonoscopy occurs commonly, but the optimal regimen for the subsequent attempt is unknown. High-volume preparations often are used but are not well studied. The objective of this study was to compare the efficacy, tolerability, and safety of 2 regimens for use after failed bowel preparation.

Methods: A multicenter, endoscopist-blinded randomized controlled trial was conducted in patients who previously failed bowel preparation despite adequate compliance. Patients were randomized to 1 of 2 split polyethylene glycol (PEG) regimens, preceded by 15 mg bisacodyl: PEG 2 L the evening before and 2 L the day of colonoscopy (PEG 2+2L+bisacodyl), or 4 L and 2 L (PEG 4+2L+bisacodyl). All patients followed a low-fiber diet on both the third and second day before the procedure, followed by a clear fluid diet the day before and the morning of the colonoscopy. The primary outcome was adequate bowel preparation, defined as a Boston Bowel Preparation Scale total score of 6 or higher, with all segment scores of 2 or higher. Secondary outcomes included adenoma detection rate, advanced adenoma detection rate, sessile serrated lesion detection, cecal intubation rate, tolerability, and adverse events.

Results: A total of 196 subjects were randomized at 4 academic centers in Canada (mean age, 60.7 y; SD, 11.4 y; 44.9% were women). There were no significant differences between the PEG 2+2L+bisacodyl and the PEG 4+2L+bisacodyl groups in achieving adequate bowel preparation (91.2% vs 87.6%; P = .44). There were no significant differences with regard to mean adenoma detection rate (37.4% vs 31.5%; P = .41), advanced adenoma detection rate (18.7% vs 11.2%; P = .16), sessile serrated lesion detection (8.8% vs 5.6%; P = .41), and cecal intubation rate (96.7% vs 92.1%; P = .19). The 2 regimens were similarly well tolerated, but PEG 2+2L+bisacodyl was associated with a higher willingness to repeat the bowel preparation (91.2% vs 66.2%; P < .001).

Conclusions: Split-dose 4 L-PEG with 15 mg bisacodyl, along with dietary restrictions, has similar efficacy as a higher-volume preparation, and should be considered for patients who previously failed bowel preparation (ClinicalTrials.gov number, NCT02976805).

Keywords: Bowel Preparation; Colonoscopy; Randomized Controlled Trial.