Low-residue versus clear liquid diet before colonoscopy: a meta-analysis of randomized, controlled trials

Background and aims: Colonoscopy is extremely important for the identification and removal of precancerous polyps. Bowel preparation before colonoscopy is essential for adequate visualization. Traditionally, patients have been instructed to consume only clear liquids the day before a colonoscopy. However, recent studies have suggested using a low-residue diet, with varying results. We evaluated the outcomes of patients undergoing colonoscopy who consumed a clear liquid diet (CLD) versus low-residue diet (LRD) on the day before colonoscopy by a meta-analysis.

Methods: Scopus, PubMed/MEDLINE, Cochrane databases, and CINAHL were searched (February 2015). Studies involving adult patients undergoing colonoscopy examination and comparing LRD with CLD on the day before colonoscopy were included. The analysis was conducted by using the Mantel-Haenszel or DerSimonian and Laird models with the odds ratio (OR) to assess adequate bowel preparations, tolerability, willingness to repeat diet and preparation, and adverse effects.

Results: Nine studies (1686 patients) were included. Patients consuming an LRD compared with a CLD demonstrated significantly higher odds of tolerability (OR 1.92; 95% CI, 1.36-2.70; P < .01) and willingness to repeat preparation (OR 1.86; 95% CI, 1.34-2.59; P < .01) with no differences in adequate bowel preparations (OR 1.21; 95% CI, 0.64-2.28; P = .58) or adverse effects (OR 0.88; 95% CI, 0.58-1.35; P = .57).

Conclusion: An LRD before colonoscopy resulted in improved tolerability by patients and willingness to repeat preparation with no differences in preparation quality and adverse effects.