Colonoscopy quality and endoscopist factors: what are the required endoscopist conditions for high- quality colonoscopy to reduce colorectal cancer incidence and mortality?

To maximize the effectiveness of colonoscopy in decreasing the incidence and mortality of colorectal cancer (CRC), high-quality colonoscopy procedures are essential. Considering that the colonoscopy quality varies among endoscopists, it is important to understand the endoscopist factors that influence the colonoscopy quality. In this paper, we reviewed the endoscopist factors related to colonoscopy quality. There are several quality indicators of colonoscopy, among which the adenoma detection rate is the most established indicator with evidence of its correlation with post-colonoscopy CRC. With respect to lesion detectability during colonoscopy, there are other measurements such as the sessile serrated lesion detection rate; however, further evidence on their relationships with post-colonoscopy CRC is needed. Previous studies that have examined the endoscopist characteristics influencing colonoscopy quality have suggested that several factors, including experience, the volume of colonoscopy procedures, and endoscopist specialty, are related to lesion detectability. However, discrepancies exist regarding the studies' results; in particular, the influence of endoscopist specialty on coloscopy quality is controversial. Some recent studies have demonstrated that endoscopist specialty is not related to lesion detectability when considering confounding factors. Furthermore, it has been reported that nurse endoscopists can provide high-quality colonoscopy after training. It may be possible for endoscopists to improve their colonoscopy quality, regardless of specialty. Training, monitoring, and feedback of colonoscopy quality measurements are useful interventions for endoscopists to ensure high-quality procedures. Owing to the continuous development of endoscopic technologies, it is believed that training is useful for both inexperienced and experienced endoscopists.