The domain for the workforce is composed of four statements (Table 2) and six quality indicators (Table 4). An endoscopist who performs EGD and CS should be an expert with the following skills: (1) the ability to perform reasonable, safe, and efficient endoscopy; (2) the ability to accurately describe and interpret endoscopic findings; (3) the ability to recognize and minimize the risk factors of endoscopy and to take appropriate action in the event of endoscopy-related complications; (4) the ability to clearly understand and provide an appropriate endoscopic diagnosis and recommended treatment for the requested exam; (5) the ability to understand the principles involved in sedative endoscopy and to conduct clinical evaluation and monitoring during sedative endoscopy; and (6) the ability to identify the importance of the reprocessing of endoscopes and to educate and perform endoscopic cleansing and reprocessing. In order to perform high-quality gastrointestinal endoscopy, an endoscopist must have the ability to diagnose and treat disease with endoscopy. In addition, they must have received supervised training for the advisement and management of gastrointestinal disease and cooperate with other specialists and assistant personnel as a part of a medical team. It is difficult to achieve an optimal level of competence in endoscopy training within a short time. Quality guidelines for gastric cancer screening define “a specialized endoscopist for EGD” as “a specialist who has undergone supervised EGD training of at least one year or more” [12], and “specialized endoscopists for CS” as “a specialist who has undergone supervised CS training in more than 150 cases over at least one year or more” [13]. In this revision, the levels of agreement and recommendation were very high for the statement regarding endoscopist qualifications and continuing medical education.

There is insufficient evidence regarding the adequate duration of and methods for gastrointestinal endoscopy training. In general, supervised gastrointestinal endoscopy training is recommended for at least one year in Korea. With regard to the optimal volume of supervised EGD procedures, 1,000 cases are recommended by both the KSGE and the Japan Gastroenterological Endoscopy Society, but only 130 cases are recommended by the American Society for Gastrointestinal Endoscopy (ASGE) [12]. Although an endoscopy specialist is not required to perform EGD screening for gastric cancer in Japan, the Japan Gastroenterological Endoscopy Society recommends at least 5 years of clinical experience and at least 1,000 cases of EGD experience for endoscopy specialists, while the Japanese Association for Cancer Detection and Diagnosis requires over three years of clinical experience, experience in over 1,000 EGD procedures, and experience with over 15 cases of gastric cancer detection for endoscopy specialists. In the Quality Guidelines for Gastric Cancer Screening [12], which were revised in 2017, it is recommended that the EGD for the NCSP should ideally be performed by an endoscopist who has undergone at least one year of supervised endoscopy or by an endoscopist with experience in at least 500 cases of EGD as the minimum qualifications [12].

For CS training, at least 1 year of supervised CS training is recommended by both the KSGE and the Korean Society of Coloproctology [13]. With regard to the volume of optimal supervised CS training, 140 and 150 cases are recommended by the ASGE and KSGE, respectively [14,15]. In the revised Quality Guidelines for CRC Screening [13], CS for the NCSP should be performed by a specialist with at least one year of supervised CS training comprising over 150 cases or an endoscopist who has performed at least 300 or more successful CS procedures as a minimum qualification. The European Society of Gastrointestinal Endoscopy recommends a minimum number of CSs to be performed annually [16]. The National Health Service Bowel Cancer Screening Programme of the United Kingdom and the Spanish Society of Gastrointestinal Endoscopy recommend at least 150 and 200 annual CSs each year for their respective national CRC screening programs [17]. Therefore, 50 cases (i.e., at least 150 cases over three years) of CS annually in Korea seems to be the minimum requirement. The strength of recommendation for the annual EGD and CS volume was intermediate with a 31.8% and 40.9% consensus, respectively.

It is well known that high-quality gastrointestinal endoscopy should be performed despite the variability in detection rates and performance by endoscopists. Yalamarthi et al. [18] reported that 6.6% of 305 patients diagnosed with gastric cancers had undergone a minimum of one EGD within the previous three years and one year, respectively. Among those patients with a definitively missed diagnosis (7.2%), endoscopist errors accounted for the majority of failures (73%). Ren et al. [19] showed that 23 (22.2%) of 103 cases of early gastric cancer/high-grade intraepithelial neoplasia had been missed on previous EGD. According to the population-based study using the NCSP database (from 2002 to 2005) by Choi et al. [20], the sensitivity of EGD screening to detect gastric cancer was only 69.0% (95% confidence interval, 66.3%–71.8%). Moreover, 2,415 gastric cancers were detected by EGD screening, and 1,083 interval cancers were detected within one year of a negative EGD screening result (rate, 1.17/1,000). Cha et al. [8] reported that endoscopist specialization is important for high-quality endoscopy in Korea, as NEQIP scores were significantly higher in the endoscopy units where endoscopy subspecialists performed the endoscopies than in those where endoscopy subspecialists did not perform them. Yamazato et al. [21] showed that 2 years of supervised endoscopy training facilitates detection of early gastric cancer by 5-fold. More studies were performed in CS given the variable detection rate among different colonoscopists. In the analysis of the results of 10,034 colonoscopies performed by nine colonoscopists between 1999 and 2004, a 2.7-fold difference was reported in the adenoma detection rate of the colonoscopists [22]. For sessile serrated adenoma, the detection rate varied by 7.3–18.0-fold [23,24]. In addition, the complete resection rate of detected polyps showed a 3.5-fold difference among colonoscopists [25]. Therefore, the qualifications and experience of the endoscopists performing EGD and CS for the NCSP are essential for a superior endoscopy.

Endoscopists must continuously receive endoscopic education to maintain endoscopic performance skills and be updated on the clinical aspects of gastrointestinal diseases at an optimal level to provide the best care [26]. The ASGE also suggests that continuous medical education (CME) for endoscopy be undertaken to maintain the endoscopists’ qualifications [27]. In the revised Quality Guidelines for Gastric Cancer and CRC Screening [12,13], at least 12 hours of CME over a three-year cycle is encouraged by attending courses aimed at endoscopic quality improvement and endoscopic reprocessing and disinfection, as well as academics and lectures. The ASGE Quality Management Committee recommends that endoscopy nursing staff should be regularly trained and educated to fulfill the responsibilities and maintain proficiency [28]. The Revised Quality Guidelines for Gastric Cancer and CRC Screening [12,13] also suggest that endoscopy nursing staff should receive CME on endoscopic management. In this revision, however, the strength of recommendation for the CME of endoscopy nurse staff in a three-year cycle was intermediate according to many votes; therefore, this gap should be considered.

The process domain is composed of 10 statements (Table 2) and nine quality indicators (Table 4). The use of a pre-procedure assessment worksheet is recommended to perform adequate and precise endoscopy. Both the ASGE and American Society of Anesthesiologists (ASA) recommend verifying past medical history and general conditions of the patient before the endoscopy procedure to confirm health status. The patient’s medical history should be checked for adverse reactions to sedatives, drug allergies, drug-drug interactions, and concurrent medications [28-30]. In the case of CS, education and written instructions for adequate bowel preparation should be provided before CS, as poor bowel preparation may lead to the postponement of CS or need for additional bowel preparation [31,32]. The risk of bleeding induced by the use of antithrombotic agents is minimal for diagnostic endoscopy, but it is important to verify their use before the procedure, as the risk of bleeding increases with therapeutic endoscopy. For patients taking anti-thrombotic agents, their underlying disease and risk of thromboembolism by temporary cessation of antithrombotics should be considered. Since CS is often followed by polypectomy, discontinuation of antithrombotic agents may further complicate CS [29]. An endoscopy must be preceded by the provision of informed consent, which should include the type of the endoscopic procedure, risk of bleeding, perforation, infection, and sedation-related adverse events [11,32-34]. Owing to the higher risks of bleeding and perforation, informed consent is mandatory, particularly for CS over EGD [11,34]. Fasting is recommended for endoscopy, and ASA guidelines recommend verifying a fasting time of 2 hours for water, 6 hours for milk and light meals, and 8 hours or more for fatty foods [35]. However, fasting time should be individualized based on the patient’s health status and diet, as longer fasting may be necessary in those with specific conditions, such as gastroparesis or achalasia [36].

Photo-documentation should be performed after careful inspection of the EGD. For EGD procedures, at least eight images should be taken, and complementary images should certainly be taken in the case of a pathologic lesion. The order in which standard images are taken will differ for each endoscopist, and it is important for the endoscopist to take images according to his or her routine so as not to miss any region. The European Society of Gastrointestinal Endoscopy recommends photo-documentation of at least 10 representative images of each of the following anatomical landmarks: the duodenum, major ampulla, antrum, angulus, fundus in inversion, greater curvature of the proximal body, greater curvature of the distal body, squamocolumnar junction, upper esophagus, and lower esophagus [37]. For CS, it is essential to take photographs of the maximal insertion site including the cecum. Cecal intubation is defined as passage of the colonoscope into a proximal part of the ileocecal valve, such that the entire cecal caput, including the medial side of the cecum between the ileocecal valve and appendiceal orifice, is visible [11,38]. When it is not clear whether the cecum has been entered, visualization of the ileocecal valve or intubation of the terminal ileum is necessary [36,39]. It is important to maintain an optimal cecal intubation rate, since low cecal intubation rates have been associated with a high incidence of proximal interval cancer. The withdrawal time should be measured for all CS procedures, and the mean withdrawal time should be kept to at least 6 minutes for negative CS [11,36,38,39]. Sufficient observation time is required for careful inspection of the CS, and a longer withdrawal time is associated with an increased adenoma detection rate. Therefore, an average withdrawal time of ≥6 minutes is recommended during CS. As various uncomfortable symptoms and complications, such as bleeding or perforation, may occur after endoscopy, it is beneficial to provide a description of possible complications, coping methods, and contact information in writing after CS. In addition, when a biopsy is performed during endoscopy, patients should be guided to check the biopsy results through an outpatient clinic [11,39]. In this revision, the level of agreement and recommendation for this domain was very high; however, considering an intermediate recommendation of 22.7% for a ≥6 minutes withdrawal time, further efforts to increase the recommendation level may be necessary.

The domain concerning facilities and equipment comprised two statements (Table 2) and two quality indicators (Table 4). Unexpected complications may occur during endoscopy, and acute bleeding may be controlled by epinephrine injection, electrocoagulation, or endoscopic clipping [40,41]. An endoscopic treatment device is particularly necessary to reduce hospitalization or transfusion for acute bleeding occurring during colonoscopic polypectomy. In addition, a cardiopulmonary resuscitation kit including an endotracheal tube should be available to handle emergency situations that may occur in patients with poor general conditions or during sedative endoscopy [11,38]. In the revision for the facilities and equipment domain, a 22.7% intermediate recommendation was observed for the separation of the endoscopy unit from the outpatient clinic, which may be due to the fact that most primary clinics divide these spaces using curtains or partitions.

The domain concerning outcome consists of four statements (Table 2) and five quality indicators (Table 4). As the quality of the gastrointestinal endoscopy is closely associated with the quality of the endoscopy report, accurate endoscopy reporting is one of the main goals of the NEQIP [37]. The endoscopy report helps to exchange information about endoscopic findings, treatment, clinical recommendations, adverse effects, and test results [11,42,43]. In order to monitor the occurrence of complications associated with endoscopy, it is necessary to record the occurrence of complications in the endoscopy report. With regard to the CS, it is essential to report the bowel preparation quality, cecal intubation, and withdrawal time to monitor the main quality indicators of CS [42,43]. Since Helicobacter pylori infection is the most common cause of peptic ulcer and successful eradication of H. pylori significantly reduces recurrence of peptic ulcers [44], the ASGE has recommended that H. pylori infection should be tested for all patients with peptic ulcers [45]. When the bowel preparation of CS is poor, the examination may be postponed or an additional bowel preparation may be necessary, which may result in inconvenience and added medical expenses for the examinee. The ASGE recommends that the frequency of adequate bowel preparation during outpatient screening CS should be over 85% [11]. Adequate bowel preparation can be defined according to the following scores: Boston Bowel Preparation Scale ≥6, Ottawa Scale ≤7, or Aronchick Scale ≥ fair [11].

In this revision, the levels of agreement and recommendation for the outcome domain were relatively high. Nonetheless, the strength of recommendation for the statement and quality indicators for H. pylori infection testing in cases of peptic ulcer were each 36.4%; therefore, it is necessary to establish a more specific definition of peptic ulcer. For example, a discussion as to whether H. pylori infection status should be assessed for peptic ulcers that are indistinguishable from scarring ulcers or erosions is warranted. Even though the levels of agreement and recommendation for the statements regarding the confirmation of an adequate bowel preparation were high, the quality indicators for the 85% adequate bowel preparation received a 59.1% intermediate recommendation; therefore, further study is needed to determine the optimal level of adequate bowel preparation.

The domain of reprocessing is composed of six statements (Table 3) and nine quality indicators (Table 5). Recently, public and health authorities have been increasingly interested in proper and safe endoscopy and endoscope reprocessing methods. For proper endoscope reprocessing, disinfection, and storage, optimal guidelines should be established and reprocessing should be performed accordingly in each endoscopy unit [46-48]. Endoscope reprocessing is classified as manual disinfection or as disinfection by an automatic reprocessor and consists of six steps: pre-cleaning, cleaning, disinfection, rinsing, drying, and storage. In 2017, an amendment to the “Guidelines for the use and disinfection of medical devices” was issued (Ministry of Health and Welfare notification No. 2017-1010) as follows: “Medicines or quasi-drugs reported to or approved by the Food and Drug Administration should be subjected to sterilization and disinfection, and the manufacturer’s instructions for each product should be followed.” Currently, the high-level disinfectants listed in the “Guidelines for the use and disinfection of medical devices” specified by the Ministry of Health and Welfare include glutaraldehyde, ortho-phthalaldehyde, peracetic acid, hydrogen peroxide, hypochlorite (produced by electrolysis at the site of use), and a material data safety sheet must be available for identification of the disinfectants and their ingredients [12,13]. Since hypochlorite, a type of electrochemical water disinfectant, is easily inactivated, water electrolysis equipment should be equipped at the site of use. It can only be recognized as a high-level disinfectant if it is used immediately after the production of hypochlorite in the field. As endoscope accessories have numerous small gaps and leaks that can be easily infiltrated by the patient’s blood or mucus, insufficient disinfection or reuse of a disposable device is vulnerable to transmission of infection [46,47]. Therefore, cleansing, disinfecting, and sterilizing an accessory device, which can cause infection transmission, is as important as reprocessing the endoscope. As high-level disinfectants may cause irritation of the eyes, skin, and respiratory system, workers who perform endoscopic reprocessing and disinfection should wear personal protective equipment, such as protective masks, gowns, and rubber gloves, and a ventilation system is required in the reprocessing room [46,47]. Recently, the continuous training, education, and surveillance of workers who perform endoscopic reprocessing and disinfection have been emphasized around the world, including in the United States and Japan.

However, it is difficult to evaluate the appropriate level of endoscopic reprocessing training for all workers in an actual clinical practice setting. Therefore, over 50% of endoscopists and reprocessing personnel are required to complete endoscopic reprocessing education programs to participate in the NCSP in Korea [12,13]. The endoscopic reprocessing education program requires the participation of experts in the endoscope disinfection field, and the education program must include hands-on courses for reprocessing workers as well as lectures. It is recommended that the endoscopy unit should be divided into a clean zone and a contaminated zone and that the endoscopy unit should be separate from the reprocessing room since the completely sterilized endoscope may be re-contaminated during storage [46,47]. Even in the reprocessing room, it is necessary to separate the clean area from the contaminated area so that the contaminated and clean endoscopes are not in close proximity. In this revision of the domain of reprocessing, the level of agreement and strength of recommendations for reprocessing were generally high. However, the level of recommendation for the statement and quality indicators regarding the wearing of personal protective equipment by workers was deemed of intermediate strength by 45.4% and 50.0% of respondents, respectively, which indicates that further education and clear definitions of personal protective equipment are necessary.

The domain of sedation is composed of three statements (Table 3) and three quality indicators (Table 5). Drug-related risk assessment should be performed and documented before sedative endoscopy to decrease the risk of adverse events and to devise a sedation plan. The pre-sedation evaluation involves mainly the ASA physical status classification system and Mallampati classification [36,49,50]. During sedative endoscopy, oxygen saturation, pulse rate, and blood pressure should be monitored to assess the condition of the examinee and check for cardiopulmonary adverse events induced by sedation. It is recommended that oxygen saturation be monitored continuously and pulse and blood pressure at 5 minute intervals [11,36,38]. Each endoscopy unit should have written discharge criteria that allow the examinees to exit the endoscopy unit after sedative endoscopy, and whether the examinees exited according to predetermined discharge criteria should be documented [11,36,38]. For example, the discharge criteria provided by the KSGE includes the following questions: (1) Are the vital signs stable?; (2) Is there any respiratory distress?; (3) Is it possible to walk without assistance?; (4) Is communication possible?; (5) Are there any abnormal symptoms such as nausea or vomiting?; and (6) Is the patient able to drink beverages without assistance? The levels of agreement and strength of recommendation for the sedation domain were generally high for the revised statement and the quality indicators.