Comparison of low volume versus high-volume polyethylene glycol-based bowel preparation for colonoscopy in people receiving haemodialysis: a randomized non-inferiority trial

Background: Colonoscopy in chronic kidney disease patients undergoing haemodialysis is crucial. Some concerns have been raised about the use of oral bowel cleansing agents for colonoscopy. We compared the efficacy, safety and tolerability of a low volume versus a high-volume polyethylene glycol-based bowel preparation for colonoscopy in such patients. Methods: A multicentre, parallel-arm, randomized, phase IV trial with 15% non-inferiority margin was conducted. Eligible subjects were allocated to either the low volume (2 L) or high-volume (4 L) bowel preparation group in 1:1 ratio. The primary outcome was the proportion of participants with adequate bowel cleansing. Secondary outcomes were polyp/adenoma detection rate (PDR/ADR), cecal intubation rate, patient tolerability/compliance and adverse events. Results: Sixty-nine patients were randomized in four centres, 35 to low and 34 to high-volume groups. No difference in caecal intubation rate, in patients with adequate preparation, was observed (96.7% vs 100%, p = 1). As per-protocol, adequate bowel preparation was achieved in the 69.7 and 63.0% of low and high-volume groups, respectively (p = 0.58). The mean Boston Bowel Preparation Scale was similar in the two groups (5.6 ± 2.4vs 5.4 ± 2.4, p = 0.51). The PDR was 39.4% in low volume and 37.0% in high volume (p = 1). No differences in adverse events were observed. No emergency dialysis sessions were required. Serum creatinine levels remained stable before and after preparation in both groups. Conclusions: Optimal cleansing was difficult to obtain in haemodialysis patients. Both low and high-volume preparations were equally effective and safe. The small sample size is a limit underpowering our research. Larger studies are, therefore, required. Trial registration number The trial was approved by the Central ethic committee (protocol approval no. 0089971/23/11/2020) and registered on ClinicalTrials.gov NCT04709770.