Cap-assisted colonoscopy versus standard colonoscopy: is the cap beneficial? A meta-analysis of randomized controlled trials

Background In an effort to improve visualization during colonoscopy, a transparent plastic cap or hood may be placed on the end of the colonoscope. Cap-assisted colonoscopy (CAC) has been studied and is thought to improve polyp detection. Numerous studies have been conducted comparing pertinent clinical outcomes between CAC and standard colonoscopy (SC) with inconsistent results. Methods Numerous databases were searched in November 2016. Only randomized controlled trials (RCTs) involving adult subjects that compared CAC to SC were included. Outcomes of total colonoscopy time, time to cecum, cecal intubation rate, terminal ileum intubation rate, polyp detection rate (PDR), and adenoma detection rate (ADR) were analyzed in terms of odds ratio (OR) or mean difference (MD) with fixed effect and random effects models. Results Five hundred eighty-nine articles and abstracts were discovered. Of these, 23 RCTs (n=12,947) were included in the analysis. CAC showed statistically significant superiority in total colonoscopy time (MD -1.51 min; 95% confidence interval [CI] -2.67 to -0.34; P<0.01) and time to cecum (MD -0.82 min; 95%CI -1.20 to -0.44; P<0.01) compared to SC. CAC also showed better PDR (OR 1.17; 95%CI 1.06-1.29; P<0.01) but not ADR (OR 1.11; 95%CI 0.95-1.30; P=0.20). In contrast, on sensitivity analysis, ADR was better with CAC. Terminal ileum intubation and cecal intubation rates demonstrated no significant difference between the two groups (P=0.11 and P=0.73, respectively). Conclusions The use of a transparent cap during colonoscopy improves PDR while reducing procedure times. ADR may improve in cap-assisted colonoscopy but further studies are required to confirm this.