One‐day versus three‐day low‐residue diet bowel preparation regimens before colonoscopy: a meta‐analysis of randomized controlled trials

Background and Aim Although studies have shown that the quality of bowel preparation with low‐residue diet (LRD) is as effective as that of clear fluid diet (CLD), there is currently no consensus on how long an LRD should last. The aim of this study was to compare a 1‐day versus 3‐day LRD on bowel preparation before colonoscopy. Methods A systematic review search was conducted in MEDLINE/PubMed, EMBASE, Web of Science, and Cochrane database from inception to April 2023. We identified randomized controlled trials (RCTs) that compared 1‐day with 3‐day LRD bowel cleansing regiments for patients undergoing colonoscopy. The rate of adequate bowel preparation, polyp detection rate, adenoma detection rate, tolerability, willingness to repeat preparation, and adverse events were estimated using odds ratios (OR) and 95% confidence interval (CI). We also performed meta‐analysis to identify risk factors and predictors of inadequate preparation. Results Four studies published between 2019 and 2023 with 1927 participants were included. The present meta‐analysis suggested that 1‐day LRD was comparable with 3‐day LRD for adequate bowel preparation (OR 0.89; 95% CI, 0.65–1.21; P = 0.45; I2 = 0%; P = 0.52). The polyp detection rate (OR 0.94; 95% CI, 0.77–1.14; P = 0.52; I2 = 23%; P = 0.27) and adenoma detection rate (OR 0.87; 95% CI, 0.71–1.08; P = 0.21; I2 = 0%; P = 0.52) were similar between the groups. There were significantly higher odds of tolerability in patients consuming 1‐day LRD compared with 3‐day LRD (OR 1.64; 95% CI, 1.13–2.39; P