Efficacy and safety of oral sulfate solution for bowel preparation in Japanese patients undergoing colonoscopy: Noninferiority‐based, randomized, controlled study

Objectives To compare the efficacy and safety of oral sulfate solution administered using the same‐day dose and the split‐dose regimens with those of polyethylene glycol plus ascorbate solution, used for bowel preparation in Japanese patients undergoing colonoscopy. Methods This multicenter (n = 13), randomized, active‐controlled, colonoscopist‐ and image evaluator‐blinded, noninferiority study with parallel‐group comparison recruited 632 patients from December 2018 to June 2019. Of these, 602 patients were divided into the oral sulfate solution same‐day dose group (n = 200); oral sulfate solution split‐dose group (n = 202); and polyethylene glycol plus ascorbate same‐day dose group (n = 200). Differences in the efficacy rates between the polyethylene glycol plus ascorbate group and each oral sulfate solution group were calculated using the asymptotic method. The safety of the oral sulfate solution was evaluated, based on the occurrence of adverse events and reactions. Results Both oral sulfate solution protocols were confirmed as noninferior to the polyethylene glycol plus ascorbate protocol for bowel‐cleansing. The occurrence of adverse reactions was significantly lower in the oral sulfate solution same‐day dose group than in the polyethylene glycol plus ascorbate group (P = 0.010). The occurrence of adverse reactions was not significantly different between the oral sulfate solution split‐dose and the polyethylene glycol plus ascorbate group. Conclusions Oral sulfate solution is not only safe and efficacious but also not inferior to polyethylene glycol plus ascorbate solution (active control). It could be used for bowel preparation in Japanese patients scheduled for colonoscopy (Clinical trial registration number: NCT03794310).