TOKYO criteria: Standardized reporting system for endoscopic biliary stent placement

Placement of a plastic or metal stent via endoscopic retrograde cholangiopancreatography (ERCP) currently serves as the first-line procedure for obstructive jaundice and acute cholangitis. Dysfunction of the biliary stent causes recurrence of symptoms and often requires reinterventions and hospitalizations. Therefore, duration of stent patency is commonly used as the primary endpoint in clinical studies of biliary stents. However, owing to considerable heterogeneity between studies in reporting of biliary stent patency, it has been difficult to compare and integrate results of indepen-dent studies. There has been between-study heterogeneity in definitions of stent patency, statistics reported for survival curves of stent patency, and methods to treat censored cases. In addition to stent occlusion, stent migration is a major cause of recurrent biliary obstruction after covered metal stent placement, which further complicates the reporting of stent patency. Reporting of functional success and adverse events has been also inconsis- tent between the studies. From the perspective of evidence-based medicine, the variations in the definitions of outcome variables potentially hinder robust meta-analyses. To overcome the issues due to the lack of outcome reporting guidelines on the topic, the TOKYO criteria 2014 for reporting outcomes associated with endoscopic transpapillary placement of biliary stents have been proposed. Due to their comprehensiveness, the TOKYO criteria can be readily utilized to evaluate various types of biliary stent placement using ERCP, irrespective of types of stents and location of biliary stricture. In this article, we review the TOKYO criteria as a standardized reporting system for endoscopically-placed biliary stents. We also discuss potential controversial issues in the application of the TOKYO criteria. Given that endoscopic ultrasound-guided biliary drainage is increasingly uti- lized for cases with failed ERCP or altered gastrointestinal anatomy, we further propose a potential application of the TOKYO criteria to reporting of outcomes of this procedure.