Annual report on National Clinical Database 2020 for gastroenterological surgery in Japan

Abstract Aim The National Clinical Database (NCD) of Japan is a nationwide data entry system for surgery, and it marked its 10th anniversary in 2020. The aim was to present the 2020 annual report of gastroenterological surgery of the NCD. Methods The data of the surgical procedures stipulated by the training curriculum for board‐certified surgeons of the Japanese Society of Gastroenterological Surgery in the NCD from 2011 to 2020 were summarized. Results In total, 5 622 845 cases, including 593 088 cases in 2020, were extracted from the NCD. The total number of gastroenterological surgeries increased gradually in these 10 years, except for the year 2020 due to the COVID‐19 pandemic. The annual number of surgeries of each organ, except the pancreas and liver, decreased by 0.4%–13.1% in 2020 compared to 2019. The surgical patients were consistently aging, with more than 20% of all gastroenterological surgeries in 2020 involving patients aged 80 years or older. The participation of board‐certified surgeons increased for each organ (75.9%–95.7% in 2020). The rates of endoscopic surgery also increased constantly. Although the incidences of postoperative complications of each organ increased by 0.7%–7.9% in these 10 years, postoperative mortality rates decreased by 0.2%–1.5%. Conclusions We present here the short‐term outcomes of each gastroenterological operative procedure in 2020. This review of the 10‐years of NCD data of gastroenterological surgery revealed a consistent increase of the number of surgeries (except for in 2020), especially endoscopic procedures, and aging of the Japanese population. The good safety of Japanese gastroenterological surgeries was also indicated.


| INTRODUC TI ON
The Japanese National Clinical Database (NCD) is a large-scale, nationwide, web-based data entry system for surgical procedures that was established with major support from the many Japanese professional surgical societies, including the Japanese Society of Gastroenterological Surgery (JSGS), and it marked its 10th anniversary in 2020. 1 The NCD has grown into a large, nationwide database covering more than 95% of the surgeries performed by general surgeons in Japan. 2 The NCD started its data registration in 2011, and since then over 5500 facilities have enrolled, and over 14 000 000 cases have been registered in 10 years. 3 The JSGS specified the 121 gastroenterological operative procedures as a requirement for board certification. Gastroenterological surgical procedures are classified into three groups according to their technical level: low, medium, and high degree of difficulty. In addition, the JSGS specified the eight major procedures (esophagectomy, distal gastrectomy, total gastrectomy, right hemicolectomy, low anterior resection, hepatectomy, pancreaticoduodenectomy, and acute diffuse peritonitis surgery) for special emphasis in terms of medical standards for improvement of surgical quality. 4 All surgical cases were registered in the NCD with the data for postoperative short-term outcomes and detailed data, such as comorbidities and morbidities, for the eight major procedures. Risk models of mortality [5][6][7][8][9][10][11][12] and morbidity [13][14][15][16][17][18][19][20][21] for these eight major procedures have been reported, which were the risk stratification studies based on all real-world Japanese data from the NCD. Based on these studies, a real-time feedback system, which includes a risk calculator for the expected mortalities and morbidities of preoperative patients, was established on the NCD website. 4 This feedback system shows each facility's severity-adjusted clinical performance compared to the national data. It also indicates the risk-adjusted cumulative expected and observed number of deaths in individual institutions.
The major purpose of the NCD is to contribute to the maintenance or improvement of medical quality. Therefore, the data registered in the NCD have been used steadily, as mentioned above.
Data reliability and disclosure are also vitally important. For the former, to assure the reliability of data of gastroenterological surgeries that had been collected by the NCD, the JSGS started data verification annually in 2015 and demonstrated the high accuracy of the accumulated data. 22,23 As for the latter, NCD annual reports, which reflect the real-world surgical outcomes of Japanese gastroenterological surgeries, have been published. [24][25][26][27] In this paper, following previous annual reports, the short-term outcomes of each gastroenterological operative procedure in 2020 will be reported.
Additionally, important findings on the changes over time in gastroenterological surgeries in Japan between 2011 and 2020 will be described.

| SUBJEC TS AND ME THODS
The subjects were patients who underwent one or more of the 121 surgical procedures specified by the Training Curriculum for Board-Certified Surgeons in Gastroenterology and had their surgical data recorded from 2011 to 2020 in the NCD system. As previously reported, [24][25][26][27] the clinical data of these patients were collected from the NCD database. Data were extracted in a secure system without any external connection, and basic statistical analysis was carried out by NCD statisticians. For each surgical procedure, the mortality rate and the number of surgical cases by sex, age, and postoperative complications were calculated. Postoperative complications that were grade III or more severe in the Clavien-Dindo (C-D) classification 28  Operative mortality was a number that combined 30-day mortality and in-hospital deaths 31-90 days after surgery.

| Annual changes in surgeries of each organ
The annual number of surgeries for each organ was decreased in organs. For the spleen, the proportion of female increased by almost 7% in the last 10 years. The ratio of age ≥80 years increased 3.8%-6.1% in the last decade (Table 3). In terms of the institution types, most cases (93%-98% in 2020) for each organ were performed in certified or affiliated institutions of the JSGS (Table 4).
The rates of postoperative complications, 30-day postoperative mortality, and operative mortality in each organ are shown in Table 5. The incidence of severe postoperative complications in the last decade was less than 5% in the gallbladder and almost 10% in the stomach and duodenum, the small intestine and colon, the rectum and anus, and the liver. Although the rate of severe complications of the esophagus and pancreas increased (4.6% and 7.9% increase in 10 years, respectively), the operative mortality rates for surgery on these organs decreased slightly in this period ( Figure 1).
The ratio of age ≥80 years increased 2.0%-7.0% in the last decade (Table 6). In terms of the institution types, most cases (94%-99% in 2020) of each procedure were performed in certified or affiliated institutions of the JSGS (Table 7). In 2020, the percentages of surgeries with participation of an anesthesiologist in each procedure were generally more than 95%. Board-certified surgeon participation rates have been increasing year by year for all procedures. The percentage of the participation of JSGS board-certified surgeons in 2020 was 96% to 98% for esophagectomy, hepatectomy, and pancreaticoduodenectomy. In contrast, the percentages were relatively low for acute diffuse peritonitis surgery (76.1% in 2020) ( Table 7).
The rates of postoperative complications, re-operation, 30-day postoperative mortality, and operative mortality in the eight major operative procedures are shown in Table 8  Operative mortality was a rate that combined 30-day mortality and hospitalization death in 31-90 days after surgery.

| DISCUSS ION
This is the first annual report of each operative procedure in the  alimentary tract surgery, except the esophagus, increased slightly to 10% from 8% in these 10 years. Furthermore, in pancreas and esophagus surgery, these incidences showed a rapid increase (up to more than 20%). Otherwise, there were the following trends: surgical cases were consistently aging; participation of board-certified surgeons increased progressively; and rates of endoscopic surgery increased. The year 2020 was the third year that robotic surgery procedures in the gastroenterological field became widely covered by insurance in Japan. The number of robotic surgeries is rapidly increasing, 31,32 and the statistics for these procedures were included as endoscopic surgeries in this report.
More than half of all patients who underwent surgical treatment in the gastroenterological field were aged 70 years or over in recent years. The rate of surgical cases for patients aged more than 70 years was 51.6% for all gastroenterological surgeries in 2020, although it was less than 40% in 2011. In particular, 2020 was the first year that the percentage of surgeries for patients aged 80 years or older was more than 20% for all gastroenterological surgeries (Table 3).
However, the operative mortalities in this decade showed a de-

TA B L E 3 (Continued)
TA B L E 4 Annual changes in surgeries of each organ by institution type and specialist participation rate  Regarding the studies of older patients in the NCD, the safety and feasibility in older rectal cancer patients were reported. 37 Furthermore, with the aging society, the number of surgeries with ileostomy or colostomy has increased gradually in Japan. 22 On the other hand, advanced age is associated with significantly worse short-term outcomes in older patients undergoing major gastroenterological elective surgeries. 38 However, any distinct cutoff age beyond which major gastroenterological surgery could be considered as being contraindicated was not identified.
In the investigation of minimally invasive surgery in the NCD, laparoscopic surgery was becoming common in surgery for acute diffuse peritonitis of gastrointestinal perforation in the data of the NCD. 39 In the pancreatic field, the outcomes of laparoscopic pancreaticoduodenectomy under the strict limitations on institutions and indications were reported comparable to those of open procedures. 40 Furthermore, robotic gastrectomy and low anterior resection in the NCD were safely performed, with low mortality and morbidity rates, either equaling or surpassing those of laparoscopic surgery. 31,32 With respect to the other issues of postoperative mortality and morbidity rates in the NCD, the impact of reconstruction route on postoperative morbidity after esophagectomy was reported. 41 The Glasgow prognostic score was shown to be strongly correlated with postoperative outcomes. 42 Moreover, the mortalities after right hemicolectomy or pancreatoduodenectomy were not affected by day of the week. 43,44 In addition, in emergency surgery for acute diffuse peritonitis, antithrombotic drug usage was associated with

TA B L E 7 (Continued)
a slight increase of intraoperative blood loss, which was thought to have little effect on clinical practice. 45 Much new evidence using the huge database of the NCD has been successively published. The NCD has contributed to quality assessment and improvement of surgery by feedback of accurate data in Japan. In conclusion, the good quality and safety of Japanese gastroenterological surgeries, which might be positively affected by the board-certification system of the JSGS, were confirmed by the 10- year data of the NCD. It is our hope that this report contributes to improving the quality of gastroenterological surgery in this country.

ACK N OWLED G M ENTS
The authors would like to thank all the medical staff, surgical clinical reviewers, and hospitals for their continued efforts in participating and entering the data for this NCD. The authors would also like to thank Mr. Keita Shimoakasho of the JSGS and Ms. Hitomi Okamoto of the NCD for their generous cooperation and providing important information for this article.