Surgical outcomes in gastroenterological surgery in Japan: Report of the National Clinical Database 2011–2019

Abstract Background We aimed to present the 2019 annual report of the gastroenterological section of the National Clinical Database (NCD). Methods We reviewed 609,589 cases recorded in 2019 and 5,029,764 cases registered from 2011 to 2019 for the 115 selected gastroenterological surgical procedures. Results The main features of gastroenterological surgery in Japan were similar to those described in the 2018 annual report, namely, that 1) operative numbers gradually increased in all procedures, except gastrectomy and hepatectomy, which decreased in these years; 2) in all eight major gastroenterological surgeries, the age distribution tended toward older patients; 3) the morbidity of esophagectomy, hepatectomy, and pancreaticoduodenectomy increased, but mortality was minimized in all procedures; 4) all eight major gastroenterological procedures have increasingly been performed under laparoscopy; and 5) board‐certified surgeons were increasingly involved. These trends in recent years were more prominent in 2019. Conclusions Thanks to the continuous cooperation and dedication of the surgeons, medical staff, and surgical clinical reviewers who registered the clinical data into the NCD, it is possible to understand the comprehensive landscape of surgery in Japan and to disclose new evidence in this field. The Japanese Society of Gastroenterological Surgery will continue to promote the value of this database and encourage the use of feedback and clinical studies using the NCD, now and in the future. Generating further approaches to surgical quality improvement are important directions for future research.


| INTRODUC TI ON
The National Clinical Database (NCD) has been recognized as the largest and best-organized nationwide surgical registry in Japan and has become indispensable for surgeons, patients, and the healthcare system of Japan. The NCD was established in 2010 and started its data registration in 2011. [1][2][3][4] As of January 14, 2021, 5 5404 facilities have enrolled in the NCD and approximately 1,500,000 cases have been registered every year, constituting more than 95% of all surgical cases in Japan. 2 The NCD comprises the members of surgery-related societies 5 including the Japan Surgical Society (JSS), the Japanese Society of Gastroenterological Surgery (JSGS), and the Japanese Society Gastroenterological surgical procedures are also classified into three groups according to their technical difficulty; low, medium, and high degree of difficulty. Some of the newly approved high-difficulty procedures, such as laparoscopic major hepatectomy and laparoscopic and robot-assisted pancreatoduodenectomy, are required to be registered preoperatively in the NCD for health insurance to be authorized by the Ministry of Health, Labour and Welfare in Japan.
Thus, the importance of the NCD has been increasing rapidly as a clinical database and a means for controlling the quality of new surgical procedures. The NCD is also important as it provides medical staff and societies with rigorously collected data for quality improvement of surgery, feedback about surgical outcomes as risk calculators for morbidities [9][10][11][12][13][14][15][16][17] and mortality, [17][18][19][20][21][22][23][24][25] data on the comprehensive surgical landscape via the NCD website, 1,5 and data gathered from various clinical studies.
This report intends to outline the current situation and trends to understand the standpoint of and to elucidate the future directions of gastroenterological surgery in Japan using data from the gastroenterological section of the NCD. Previously, the annual reports of the NCD were published on data from 2011 to 2018, and more than 609,589 cases were newly registered in 2019. We describe the most important findings from the data about gastroenterological surgery in the NCD between 2011 and 2019.

| SUBJEC TS AND ME THODS
As previously reported, 6-8 the subjects were patients who collectively underwent the 115 surgical procedures stipulated by the "Training F I G U R E 1 Annual changes in the number of surgeries, 30-day mortality, operative mortality, and complications: Analysis of the 115 surgical procedures. Postoperative complication rate: the rate of Clavien-Dindo (C-D) classification grade III (complications requiring intervention) or higher complications TA B L E 1 Annual changes of surgeries by sex, age group, and organ for the selected 115 gastrointestinal operative procedures in the training curriculum for board-certified surgeons in gastroenterology into the NCD and linked with each procedure to elucidate the participation of board-certified surgeons.
Data were extracted in a secure system without external connection and basic statistical analysis were carried out by NCD statistic experts, and the number of surgical cases and the mortality rates related to the selected 115 gastroenterological operative procedures were calculated, as well as those for the eight major operative procedures from 2011 to 2019. The incidence of participation of boardcertified surgeons as the primary surgeons or assistants in the eight major gastroenterological surgeries was also calculated.

| The 115 selected gastroenterological operative procedures in the "Training Curriculum for Board-Certified Surgeons in Gastroenterology"
The total number of cases represented by the 115 selected gastroenterological surgical procedures, recorded in the NCD from January 1 to December 31, 2019, was 609,589, and 5,029,764 cases were registered between 2011 and 2019 ( Figure 1). Regarding organ involvement, the stomach and duodenum decreased slightly to 63,160 The rate of postoperative complications and 30-and 90-day mortalities are described in Table 3. The rate of complications in the esophagus, stomach and duodenum, pancreas, and spleen increased slightly toward 2019, while the mortality decreased in these organ groups. The rate of complications and 30-90-day mortality in the rest of the organs were approximately the same as before.

| Eight major operative procedures
The number of surgeries carried out annually for the eight major operative procedures, the percentage by gender, and the percentage according to age group between 2011 and 2019 are shown in Table 4 ( Figure 2).
The number of procedures increased in RHC, LAR, and PD and decreased in DG, TG, and HEP.
The age distributions mirrored the tendency in recent years to shift toward older patients, and the percentage of cases with the age  (Table 5).

F I G U R E 2
Annual changes in the number of surgeries, 30-day mortality, operative mortality, and complications: Analysis of the eight major surgical procedures. Postoperative complication rate: the rate of Clavien-Dindo (C-D) classification grade III or higher complications TA B L E 5 Institution and anesthesiologist and specialist participation rates by organ for eight main operative procedures

| D ISCUSS I ON
Data of gastroenterological surgery in Japan using the gastroenterological section of the NCD were summarized, and the trends in the 115 gastroenterological procedures and eight major gastroenterological surgeries were reported. The numbers, demography, morbidities, and mortalities of the procedures comprised the main contents of this report, summarized as follows: 1) Operative numbers gradually increased in all procedures except for gastrectomy and hepatectomy, which decreased in these years; 2) age distributions shifted toward older patients in all eight major gastroenterological surgeries; 3) morbidities of ESO, HEP, and PD increased, but the mortalities were minimized in all procedures; 4) laparoscopic   and mortalities were higher, and the rate of involvement of board-   36 and PD. 37 The Endoscopic Surgical Skill Qualification System certification by the Japan Society for Endoscopic Surgery did not affect the postoperative mortality following laparoscopic DG and LAR. 38 Additionally, hospital volume affected postoperative mortality after TG 39 and PD, 40 and laparoscopic liver resection was safely developed with a low mortality and complication rate relative to open liver resection in Japan. 41 A geriatric surgery pilot study was conducted from 2017 to 2020, and the specific variables and outcome predictors in geriatric surgery were implemented in the NCD system in 2021. 42 Thus, in the NCD, a robust nationwide registry on surgical outcomes is important to elucidate the performance of surgeries, to provide tools for future studies, and to improve the surgical outcomes.
The database itself is only a result of the clinical treatment, but it is important for establishing the four pillars of surgical quality improvement that the American College of Surgeons-National Surgical Quality Improvement Program (ACS-NSQIP) has identified. 43 These four pillars are setting standards, creating the infrastructure required to achieve these standards, commitment to measuring performance against those standards and remaining accountable for those measurements, and agreeing to a peer review against those standards. The JSGS and ACS-NSQIP have collaborated since the foundation of the NCD in 2010, and collaborative studies are ongoing. 3,44 Rigorous data collection is required with respect to the third pillar. While the other pillars are important, establishing standards could be the essential step.
Besides the data presented in this annual report, many other variables were also available, and future studies are expected to elucidate the current situation and implications for the future. Further active clinical studies will discover new evidence using the assets of the NCD data, which all surgeons, medical staff, and surgical clinical reviewers contributed to, in most facilities in Japan. We continuously take care to promote the value of the database and to encourage the usage of feedback and clinical studies using the NCD now and in the future.

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

E TH I C A L A PPROVA L
The protocol for this research project has been approved by the Ethics Committee of the NCD as of November 18, 2020, and it con-