Simethicone decreases bloating and improves bowel preparation effectiveness: a systematic review and meta-analysis

Background Simethicone is an adjunct frequently used during bowel preparation before colonoscopy and currently there is no consensus on whether it should be recommended in standard bowel preparation. We performed a systematic review and meta-analysis to determine the effect simethicone has on bowel cleanliness, adenoma detection rate (ADR), and tolerability. Methods We searched the literature for studies that compared colon cleansing of patients that received standard bowel preparation alone and in combination with simethicone prior to colonoscopy. The primary outcomes were colon cleanliness, ADR, and tolerability. Results Sixteen randomized controlled trials with 5630 patients were included in meta-analysis. Overall, polyethylene glycol (PEG) with simethicone improves colon cleansing compared with PEG alone (odds ratio [OR] 1.48, CI 1.11 to 1.97, P = 0.008). This improvement was seen for single dosing (OR 1.83, CI 1.20 to 2.79, P = 0.005) but not for split dosing (OR 1.32, CI 0.72 to 2.43, P = 0.38). Overall, simethicone had no effect on ADR (OR 1.22, CI 0.81 to 1.83, P = 0.33), but in patients receiving single dosing, simethicone significantly increased ADR (OR 1.96, CI 1.22 to 3.16, P = 0.005). The rates of nausea (OR 0.96, CI 0.75 to 1.24, P = 0.75), vomiting (OR 1.00, CI 0.69 to 1.44, P = 0.99), and abdominal pain (OR 0.69, CI 0.40 to 1.18, P = 0.17) were not significantly different between PEG and PEG + simethicone cohorts. For abdominal bloating, the PEG cohort had greater odds of experiencing bloating than the PEG + simethicone cohort (OR 2.33, CI 1.70 to 3.20, P