Low-volume vs High-volume Polyethylene Glycol Based Bowel Preparation for Colonoscopy in People Receiving Hemodialysis

Study design: This will be a multicentre, outcome assessor-blinded, parallel-arm, centrally randomized, non-inferiority trial. Randomization will be performed centrally by the coordinating center. Consecutive inpatients and outpatients on hemodialysis with an indication to undergo colonoscopy (positive fecal occult blood test or fecal immunochemical test, signs or symptoms of colorectal disease, colorectal cancer screening, colorectal cancer surveillance, inflammatory bowel diseases, or inclusion in kidney transplantation waiting list) will be screened for inclusion in the trial. At enrolment visit, eligible subjects will be allocated to either the low-volume or high-volume bowel preparation group (ratio 1:1). Participants in the low-volume group will receive the formulation of 2-liters polyethylene glycol with citrate and simethicone (Clensia, Alfasigma S.p.A., Milan, Italy), while those in the high-volume arm will receive 4-liters polyethylene glycol with simethicone (Selg Esse, Alfasigma S.p.A., Milan, Italy). Participants in both groups will be prescribed a low residue diet for 3 days before colonoscopy and will be instructed to take the bowel cleansing agents as split dose, taking the first half of solution the evening before the endoscopic examination and the second in the morning of the day of the procedure. To improve compliance, participants will also receive a booklet in plain language to explain the details of low residue diet and modality of bowel preparation intake. All endoscopic examinations will be scheduled on days free from dialysis sessions between 2 and 5 hours after the end of the administration of the last dose of preparation. On the day of the colonoscopy, all participants will fill in a questionnaire to measure participants' compliance, tolerability, and willingness to repeat the preparation they have been allocated to. Participants will be aware of the bowel preparation they received. On the opposite, endoscopists and nephrologists measuring primary and secondary outcomes (i.e. outcome assessors) will be blinded to the arm each subject has been allocated to and instructed to avoid any discussion with participants that could reveal the type of bowel cleansing agent. Recruitment will last 12 months and follow-up will be completed 1 month after the last participant undergoes colonoscopy. Before randomization and during the one-month follow-up, participants will receive (in a non-randomized fashion) all relevant co-interventions (e.g. iron, lipid-lowering agents, bone disease agents, antihypertensive agents, etc.), which are peculiar of standard hemodialysis treatment, as per their usual attending physician's practice to achieve and maintain standard hemodialysis clinical performance measures. At the time of enrolment and colonoscopy scheduled simple trial follow-up visits will be performed. All clinical events following the endoscopic procedure will be measured during the one-month follow-up period.