Table 3.

Secondary outcomes

Procedures	Radiation exposure-related factors
ERCP	Surgically altered gastrointestinal anatomy. Billroth I reconstruction, Billroth II reconstruction, Roux-en-Y reconstruction and pancreaticoduodenectomy Type of endoscope. Naïve papilla. Indications for ERCP (including suspicion) are classified into the following five categories: Choledocholithiasis (maximum diameter, number of stones, presence of cholangitis, tube exchange for the above diseases, treatment for choledocholithiasis with or without balloon catheter, basket catheter, crusher, etc). Distant malignant bile duct stricture (papillary tumour, distal cholangiocarcinoma, pancreatic cancer, etc). Proximal malignant bile duct stricture (Hilar cholangiocarcinoma, intrahepatic cholangiocarcinoma, gallbladder cancer, etc). Pancreatic duct examination (pancreas cancer, intraductal papillary mucinous neoplasm, etc). Other diseases apart from those listed above (benign bile duct stricture, pancreatobiliary junction abnormality, etc). Total procedure time (min).* Cannulation time. Treatment time. Experience of the HVE or LVE.† Facility scale: the number of ERCP procedures per year. Whether the fluoroscopic operator is inside or outside in the fluoroscopy room. Various treatments (endoscopic sphincterotomy, stone treatment, bile duct/pancreatic stent, cytology, biopsy, naïve papilla, cannulation method, contrast agent, intubation time, first-use catheter, large balloon, crusher, drainage area or method, stent type used and cholangioscopy). Sedation: medication and the depth of the anaesthesia.‡
Interventional EUS	Indication for interventional EUS (EUS-guided hepaticogastrostomy), choledochoduodenostomy, cyst drainage, antegrade treatment, rendezvous technique and pancreatic duct drainage. Total procedure time.‡ Endoscope insertion time. Treatment time. Facility scale: the number of EUS interventions per year and the number of EUS-guided fine-needle aspiration procedures per year. Double stenting (presence or absence of duodenal stenosis). Device. Scope position. Sedation: medication and the depth of anaesthesia.
Balloon-assisted enteroscopy	Disease indicating balloon-assisted enteroscopy. Hemostatic or bleeding confirmation. Crohn’s disease. Small intestine tumour examination. Others. Insertion site: perioral or transanal. Insertion length (cm). Total procedure time (min).
Enteral metallic stent placement	Stent location. Oesophagus (upper/mid-low/trans). Gastro-duodenum (above pylorus/trans pylorus/below pylorus). Colon stent (right/left/rectum). Total procedure time (min).§ Endoscope insertion time. Treatment time.
Enteral ileus tube placement	Disease indicating ileus tube. Intranasal ileus tube insertion for ileal obstruction or transanal ileus tube insertion for malignant colonic obstruction. Tube insertion length for peroral ileus tube placement (cm). The occlusion site for the transanal tube (right/left/rectum). Total procedure time (min).¶

*Cannulation time is defined as the time from endoscope insertion until successful biliary cannulation, and treatment time is defined as the time from successful biliary cannulation until the scope is removed from the patient. The total procedure time is defined as the time from endoscope insertion until the scope is removed from the patient (cannulation time+treatment time).

†HVE: endoscopists with more than 200 ERCP results and who have been involved in ERCP for over 10 years. LVE: non-HVE endoscopists who perform ERCP.

‡Depth of anaesthesia is divided into three levels based on the RASS, Ramsay Scale and SAS: good, poor and very bad. The good level is defined as RASS score: −5–−1, SAS score: 1–3 and Ramsay score: 3–6 equivalent, without additional unplanned doses. The poor level is defined as RASS score: 0–+1, SAS score: 4–5 and Ramsay score: 1–2, without physical restraint but with unplanned doses. The very bad level is defined as requiring physical restraint with a force considered dangerous, RASS score: +2–+4, and SAS score: 6–7 regardless of Ramsay score.

§Endoscope insertion time is defined as the time from endoscope insertion until the initial EUS-guided needle puncture, and treatment time is defined as the time from initial EUS-guided needle puncture until the scope is removed from the patient. The total procedure time is defined as the time from endoscope insertion until the scope is removed from the patient (endoscope insertion time + treatment time).

¶Endoscope insertion time is defined as the time from endoscope insertion until initial guidewire exploration, and treatment time is defined as the time from initial guidewire exploration until the scope is removed from the patient. The total procedure time is defined as the time from endoscope insertion until the scope is removed from the patient (endoscope insertion time + treatment time).

ERCP, endoscopic retrograde cholangiopancreatography; EUS, endoscopic ultrasonography; HVE, high-volume endoscopist; LVE, low-volume endoscopist; RASS, Richmond Agitation-Sedation Scale; SAS, Sedation-Agitation Scale.