Zhao S, et al. - Via performing meta-regression analyses, researchers comprehensively evaluated the adenoma miss rate (AMR) and advanced AMR (AAMR) and explored associated factors. For this systematic review and meta-analysis, PubMed, Web of Science, and Ovid EMBASE databases were searched for studies published through April 2018 on tandem colonoscopies, with AMR and AAMR as the primary outcomes. Investigators observed that miss rates were high for proximal advanced adenomas, serrated polyps, flat adenomas, and in patients at high risk for colorectal cancer. They suggested that miss rates could be lessened by adequate bowel preparation and auxiliary techniques. Findings suggested an independent association of the adenoma detection rate (ADR), adenomas per index colonoscopy, and adenomas per positive index colonoscopy (APPC) with AMR. On the other hand, APPC was the only factor independently related to AAMR. More frequently than previously thought, adenomas and advanced adenomas are missed (based on AMR and AAMR). In addition to ADR, if validated in additional studies, APPC should be considered as an indicator of colonoscopy quality.