THE EFFICACY OF COMBINING SIMETHICONE AND POLYETHYLENE GLYCOL FOR ADENOMA DETECTION DURING COLONOSCOPY: A SYSTEMATIC REVIEW AND META-ANALYSIS OF RANDOMIZED CONTROLLED TRIALS

Background Although several randomized controlled trials (RCTs) have shown that the addition of simethicone to polyethylene glycol (PEG) can improve bowel preparation, whether PEG plus simethicone had a beneficial role in the adenoma detection rate (ADR) during a colonoscopy has yet to be confirmed. The aim of this study was to clarify whether adding simethicone to a PEG solution could improve the effectiveness of the ADR. Methods The PubMed, EMBASE, and Cochrane Library databases were searched for articles published prior to November 2018. The primary outcomes included the ADR and the polyp detection rate (PDR). The secondary endpoints included the efficacy of the colon preparation, procedure-related parameters, adverse events and willingness to repeat preparation. The odds ratios (ORs) and mean difference (MD) with 95% confidence intervals (CIs) were pooled for discrete and continuous variables. The subgroup analyses and sensitivity analyses were performed. Results Eighteen studies were eligible. Although there was no significant difference in the overall ADR (OR =1.03, 95% CI: 0.89-1.18, P=0.73) between the groups with or without simethicone, a significant effect of simethicone for small adenomas (<1 cm) on the ADR was revealed (OR=2.36; 95% CI, 1.79-3.10; P<0.00001). The subgroup analyses showed the beneficial effects of simethicone in the ADR among Asian populations (OR=1.45, 95% CI = 1.12-1.87, P=0.005) and the baseline ADR <25% (OR=1.55, 95% CI = 1.16-2.07, P=0.003). Moreover, there was a significant difference in the right-side ADR (p=0.002) and borderline statistical significance in the left-side ADR (p=0.04) between the two groups. In addition, adding simethicone to the PEG solution improved bowel preparation and patient acceptability. (figure 1a) Conclusions In summary, we believe that the addition of simethicone to PEG is a promising bowel preparation method for colonoscopy in clinical practice among Asian populations. Additional large clinical trials are necessary to validate our results.