Effect of oral simethicone on the quality of colonoscopy: A systematic review and meta-analysis of randomized controlled trials

Objective In this systematic review and meta-analysis, we aimed to investigate the effect of oral simethicone (SIM), an antifoaming agent, on the quality of colonoscopy in terms of bowel preparation quality, adenoma or polyp detection rate (ADR/PDR) and cecal intubation rate (CIR). Methods All randomized controlled trials (RCTs) on the use of SIM during bowel preparation for colonoscopy published up to 17 March 2021 were identified from the PubMed, EMBASE and Cochrane Library databases. Bowel preparation quality, ADR/PDR/CIR, cecal intubation time (CIT), withdrawal time (WT), patients' tolerability, acceptability and volume of foam and bubbles were compared between the SIM and non-SIM groups. Results Thirty-eight RCTs with 10 505 patients were included. Oral SIM significantly increased the rate of total Boston bowel preparation scale (BBPS) score >= 6 (risk ratio [RR] 1.13, P < 0.0001), acceptability (RR 1.15, P = 0.01) and the rate of no or minimal foam and bubbles (RR 1.28, P < 0.00001) and decreased abdominal distension (RR 0.64, P < 0.0001). However, it had no significant impact on overall ADR, overall PDR, CIR, CIT or WT. The rate of total BBPS score >= 6 remained significantly higher in the SIM group when a single-dose laxative regimen or a SIM dosage of >= 320 mg was employed; and ADR, PDR and CIR were significantly increased in the SIM group among colonoscopy clinicians who achieved an ADR <31%, PDR <45% and CIR <96%, respectively. Conclusions Oral SIM can improve bowel preparation quality, especially in patients receiving a SIM dosage of >= 320 mg or a single-dose laxative regimen. SIM may be preferred by junior colonoscopy physicians/trainees with a lower ADR/PDR or CIR.