Low-residual diet versus clear-liquid diet for bowel preparation before colonoscopy: meta-analysis and trial sequential analysis of randomized controlled trials

The aim of this study was to compare a low-residual diet (LRD) with a clear-liquid diet (CLD) for bowel preparation before colonoscopy. A systematic literature search was performed in PubMed, Ovid, and Cochrane databases for randomized clinical trials comparing LRD with CLD for bowel preparation before colonoscopy. The last search was performed on September 20, 2019. The primary outcome was adequate bowel preparation. The outcomes were compared using systematic review with meta-analysis and trial sequential analysis (TSA). Twenty randomized controlled trials published between 2005 and 2019 with 4323 participants were included. LRD was comparable with CLD for adequate bowel preparation (P = .79; odds ratio [OR], 0.96; 95% confidence interval [CI], 0.72-1.29). The detection rates for polyps (P = .68; OR, 1.04; 95% CI, 0.86-1.27) or adenomas (P = .78; OR, 1.03; 95% CI, 0.86-1.23) were similar between the groups. There were significantly fewer advents in individuals in the LRD group: nausea (P = .02; OR, 0.72; 95% CI, 0.56-0.94), vomiting (P = .04; OR, 0.61; 95% CI, 0.38-0.98), hunger (P < .001; OR, 0.36; 95% CI, 0.24-0.53), and headache (P = .02; OR ,0.64; 95% CI, 0.44-0.93). In addition, significantly more individuals in the LRD group found it easy to complete the diet (P = .01; OR, 1.86; 95% CI, 1.15-3.00) and showed willingness to repeat it (P = .005; OR, 2.23; 95% CI, 1.28-3.89). TSA demonstrated that the cumulative Z curve crossed both the traditional boundary and the trial sequential monitoring boundary for adequate bowel preparation. The present study demonstrated that LRD was comparable with CLD in the quality of bowel preparation before colonoscopy. More clinical trials are needed to confirm other outcomes. [Display omitted]