Efficacy of single- versus split-dose polyethylene glycol electrolyte solution for morning colonoscopy: A randomized controlled study

BACKGROUND: Split-dose (SPD) regimen has been proved more effective than a single-dose (SID) regimen for various drug preparations; however, limited data have focused on morning colonoscopy. We implemented this study to compare the bowel cleanliness and tolerability of a same-day SID versus SPD 2 L polyethylene glycol electrolyte solution (PEG) for morning colonoscopy. METHODS: Patients undergoing morning colonoscopy were randomized into two groups, SID or SPD. In the SID group, patients had to complete 2 L PEG between 4 and 6 am on the day of colonoscopy. In the SPD group, patients had to complete 1 L PEG between 8 and 9 pm on the day before followed by another 1 L PEG between 5 and 6 am on the day of colonoscopy. Colonoscopy was performed between 8 and 12 am under anesthesia. Investigators and endoscopists were blinded to the allocation. The primary end point was the effectiveness of bowel cleansing according to the Boston Bowel Preparation Scale (BBPS). The secondary outcomes were polyp detection rate, compliance, tolerability, and patient satisfaction. RESULTS: Overall, there were 147 and 148 patients in the SID and SPD group, respectively. The SPD group had a better quality of bowel preparation than the SID group with a total BBPS score of 7.25 ± 1.53 versus 6.71 ± 1.65 (P = 0.005). No difference in the polyp detection rate was noted, although more polyps were detected in the SPD group. More patients felt acceptable with the bowel preparation regimen in the SPD group compared to the SID group (76% vs. 65%, P = 0.03). The adverse events were more commonly observed in the SID group, presented as nausea and vomiting. CONCLUSION: For morning colonoscopy, split-dose 2 L PEG is superior to single-dose 2 L PEG by improved bowel preparation, better tolerability, and patient satisfaction.