Gastrointestinal Intervention 2018; 7(2): 46-51  https://doi.org/10.18528/gii180016
TOKYO criteria: Standardized reporting system for endoscopic biliary stent placement
Tsuyoshi Hamada1, Yousuke Nakai1, and Hiroyuki Isayama2,*
1Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan, 2Department of Gastroenterology, Graduate School of Medicine, Juntendo University, Tokyo, Japan
*Department of Gastroenterology, Graduate School of Medicine, Juntendo University, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan. E-mail address:isayama-tky@umin.ac.jp (H. Isayama). ORCID: https://orcid.org/0000-0002-3308-9326
Received: May 2, 2018; Accepted: July 11, 2018; Published online: July 31, 2018.
© Society of Gastrointestinal Intervention. All rights reserved.

cc This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract

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 independent 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 inconsistent 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 utilized 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.

Keywords: Cholangiopancreatography, endoscopic retrograde, Common bile duct, Endosonography, Jaundice, obstructive, Self expandable metallic stents
Introduction

In clinical research, a standardized outcome reporting system is mandatory to interpret study results appropriately and to ensure comparability of different studies. The study results reported based on different reporting systems may be difficult to be compared and integrated, potentially compromising robust pooled- and meta-analyses.1 The STROBE (STrengthening the Reporting of OBservational studies in Epidemiology),2 CONSORT (CONsolidated Standards Of Reporting Trials),3 and PRISMA (the Preferred Reporting Items for Systematic reviews and Meta-Analyses)4 statements have been successfully utilized for reporting results of observational cohort studies, randomized controlled trials (RCTs), and meta-analyses, respectively. However, those guidelines have focused mainly on standardization of essential and general items that should be reported in corresponding types of studies. Therefore, clear and standardized definitions of outcome variables are required for a specific research topic of interest.

Endoscopic placement of a biliary stent has remained a cornerstone of management of benign and malignant biliary strictures.510 In clinical studies of biliary stents, duration of stent patency is often used as the primary outcome variable and typically defined as the time between stent placement and dysfunction. The duration of stent patency directly affects patients’ quality of life and burden of health care costs: that is, longer stent patency is associated with fewer procedures, less frequent hospitalizations, and lower costs.11,12 In addition, the time-point of stent dysfunction is readily determined based on symptoms and/or laboratory tests.13 However, the definitions of stent patency and the statistics used for reporting of duration of stent patency have been considerably heterogeneous across the studies, such that comparisons and integrations of the results of studies conducted in different settings have been largely hindered. For example, due to the heterogeneity in reporting stent patency across the studies,11,1436 only a fraction of RCTs comparing different types of biliary stents for nonresectable distal malignant biliary obstruction (MBO) have been used for meta-analyses.3741 Several statistical methods are available for imputation of missing outcome data, these methods have inherent bias and are not always feasible.37,42,43 Therefore, there is a great need for specific guidelines for reporting of outcomes associated with endoscopically-placed biliary stents.

Under these circumstances, the TOKYO criteria for transpapillary biliary stenting were proposed in 201444 and are increasingly utilized in clinical studies of endoscopic biliary stents.4561 As illustrated in Fig. 1, these guidelines have standardized the definitions and reporting of procedure-related outcomes, stent-related outcomes, and adverse events. In this article, we review the TOKYO criteria and discuss several issues that researchers may encounter when using the criteria in clinical settings. We further propose an application of the TOKYO criteria to reporting of outcomes of endoscopic ultrasound (EUS)-guided biliary drainage that is increasingly utilized as an alternative to ERCP for cases with endoscopic transpapillary biliary access unavailable.6268

Reporting of Recurrent Biliary Obstruction

Dysfunction of plastic stents and uncovered self-expandable metal stents (SEMSs) is caused predominantly by occlusion due to tumor ingrowth/mucosal hyperplasia (for uncovered SEMSs), biliary sludge, and/or food impaction.69 Therefore, duration of stent patency served as a reasonable surrogate for clinical benefits from a specific type of biliary stent. Subsequently, covered SEMSs were developed to prevent tumor ingrowth and thereby prolong time to dysfunction in patients with nonresectable distal MBO.14 Covered SEMSs are more prone to migration after placement compared with plastic stents and uncovered SEMSs.40,41 While removability is another strength of covered SEMSs,69,70 further expanding their indication to benign biliary strictures,71,72 evaluation of stent patency is censored at the time of stent removal. Accordingly, in the current clinical practice, we often encounter various types of outcomes associated with biliary stents as well as stent occlusion. Consequently, evaluating outcomes of biliary stents has become complicated, and the terminology for stent-related outcomes has been inconsistent.

Recurrent biliary obstruction (RBO) has been defined as a composite endpoint of either occlusion or migration, and TRBO has been defined as the time from stent placement to RBO or patient death, whichever comes first.44 From the perspective of patient care, an endoscopic reintervention and additional hospitalization are usually needed both for stent occlusion and migration such that deterioration in patients’ quality of life and burden on health care costs are considered comparable between these two causes of RBO. Therefore, the composite endpoint as an indicator for stent dysfunction is considered reasonable. Another strength of the use of TRBO as an outcome variable in studies of biliary stents is that the estimation of TRBO is not sensitive to potential misclassifications of stent occlusion and migration. It is occasionally difficult to differentiate stent occlusion and migration as causes of RBO after covered SEMS placement: e.g., based on findings of complete occlusion due to biliary sludge in a migrated covered SEMS, we would speculate that the migration might be due to the intrabiliary pressure enhanced by stent occlusion. Fig. 2 summarizes the items that should be included in reporting of RBO and TRBO after biliary stent placement. Stent occlusion has been defined as presence of biochemical evidence on cholestasis (i.e., elevated liver enzymes as compared with baseline values) along with biliary dilation on imaging studies, or endoscopic findings suggesting it.44 Causes of stent occlusion are categorized as tumor ingrowth/mucosal hyperplasia, tumor overgrowth, biliary sludge with/without stones, food impaction, hemobilia, and others (kinking of the bile duct due to a SEMS, SEMS collapse, etc.). Stent migration has been defined as presence of endoscopic findings of a completely or partially migrated stent at the time of a reintervention for patients with RBO.44 It is recommended that, in cases with asymptomatic stent migration, the time-point of migration is set as the point when symptoms associated with stent migration are observed.

Non-occlusion cholangitis has been defined as a high-grade fever (> 38°C) which continues longer than 24 hours without deterioration in dilation of the drained bile duct or a definite finding of stent occlusion or migration at the time of a reintervention.44 In cases with distal MBO, this type of cholangitis is typically observed after placement of a SEMS which has a large luminal diameter and compromises the sphincter function.7375 Non-occlusion cholangitis may require medications, interventions, and/or a hospitalization, and thus, pose similar burden to occlusion or migration as a cause of RBO. Therefore, non-occlusion cholangitis that requires interventions including stent removal may be categorized as an event in evaluation of RBO for cases with distal MBO, although this condition has not been defined as a cause of RBO in the TOKYO criteria.

Information on causes of RBO and timing of RBO due to specific causes may help us to characterize and improve clinical outcomes of SEMSs, because structures and mechanical properties of SEMSs play a key role in determining the risk of RBO.76,77 For example, higher levels of axial force, which is defined as shape recovery force from a bending to straight position, have shown to be associated with a higher risk of covered SEMS migration.78 Based on the observations of premature stent occlusion due to the duodenobiliay reflux characterized by biliary sludge and food impaction,79,80 researchers were motivated to develop biliary stents with an antireflux valve.8184

As a substantial proportion of patients with periampullary malignancy die without RBO owing to the aggressiveness of underlying diseases, TRBO is usually estimated using the Kaplan-Meier method that takes censored cases into account, and is compared between groups using the log-rank test. TRBO is underestimated when patient’s premature death without RBO is treated as censored in the Kaplan-Meier method,85 and thus, data on patient survival in each study-arm are required to interpret the results of TRBO appropriately. Recently, a competing risk analysis86 is increasingly utilized to evaluate stent patency while mitigating a potential bias due to patient’s death as a competing risk event.8790 A competing risk analysis treats death without RBO as informative censoring as opposed to non-informative censoring in the conventional Kaplan-Meier method. Although application of the competing risk analysis to all clinical trials of biliary stents should be further discussed, this statistical method may mitigate the bias due to unbalanced survival times between the groups that is typically observed in retrospective studies. In addition, this analysis serves as a powerful tool that provides less biased estimations of cumulative curves when cumulative incidence functions for TRBO due to specific causes (e.g., stent occlusion and migration) are examined separately. Namely, in this analytic framework, the summation of all cumulative incidence functions remains one at all time-points.

Reporting of Technical and Functional Successes

Technical and functional successes are assessed as immediate outcomes associated with biliary stent placement and are particularly important at the phase of pilot studies. Technical success has been defined as successful placement of a stent in the intended location with sufficient coverage of a target biliary stricture.44 The definitions of functional success have been considerably different across the studies. In the TOKYO criteria, functional success has been defined as a 50% decrease or normalization of total serum bilirubin level within 14 days of stent placement.44 For biliary stents placed for cholangitis without obstructive jaundice (e.g., segmental cholangitis) or cholecystitis,91 functional success can be alternatively defined as cessation of antibiotics or a 50% decrease or normalization of levels of blood inflammatory markers within 14 days of stent placement.

Failure in stent placement and thus technical failure pose a challenge for evaluations of biliary stents in RCTs. In RCTs, intension-to-treat (ITT) analyses are recommended rather than per-protocol analyses and are widely utilized. However, for cases where biliary drainage has not been carried out, clinical outcomes including RBO and TRBO cannot be evaluated. In patients who undergo an alternative modality of biliary drainage (e.g., surgical choledochojejunostomy and percutaneous biliary drainage), interpretations of causes of RBO, TRBO, and adverse events should be different from those in patients who receive biliary drainage via ERCP. Therefore, per-protocol analyses are considered acceptable for evaluations of stent-related outcome variables. Nonetheless, patient survival time can be evaluated using ITT analyses.

Reporting of Adverse Events

Fig. 3 summarizes how adverse events associated with endoscopic placement of biliary stents can be reported. Etiologies of the adverse events are generally categorized as procedure-related and stent-related, which are occasionally difficult to be differentiated. The TOKYO criteria recommend reporting types and severity of adverse events, irrespective of underlying etiologies.44 Reporting the timing of occurrence of adverse events (within 30 days of stent placement vs 31 days or later) may help characterize the risk of adverse events due to specific stent types. For example, pancreatitis usually occurs as post-ERCP pancreatitis within a few days of the procedure, but may develop several months later based on obstruction of the pancreatic duct orifice due to a SEMS with high axial force.92

The adverse events associated with biliary stents include pancreatitis, non-occlusion cholangitis, cholecystitis, and others (e.g., bleeding, perforation of the gastrointestinal tract). The landmark consensus criteria proposed by Cotton et al93 have been long utilized to define and grade adverse events associated with ERCP. In 2010, the American Society of Gastrointestinal Endoscopy lexicon guidelines were proposed as a comprehensive scheme for documenting and grading of adverse events associated with endoscopic procedures.94 The TOKYO criteria have integrated and customized these guidelines specifically for evaluation of adverse events associated with endoscopic placement of biliary stents. The adverse events associated with biliary stent placement have been rarely defined in articles, but can be documented consistently using the local clinical criteria at each institution. However, there are challenges in evaluation of cholangitis as an adverse event. In the TOKYO criteria, cholangitis due to RBO is not classified as occurrence of an adverse event, but as RBO due to respective causes. As described above, non-occlusion cholangitis after stent placement for distal MBO may be considered as an event in evaluation of RBO when interventions are required. However, non-occlusion cholangitis is often managed conservatively by administration of antibiotics and is difficult to be differentiated from other infectious diseases. Therefore, non-occlusion cholangitis without requirement of interventions can be documented as an adverse event so that evaluation of TRBO is not censored at the time of this adverse event.44 Using this definition, segmental cholangitis caused by obstruction of the biliary brunch due to stent placement or cholangitis in the undrained brunch can be dealt as non-occlusion cholangitis among cases with hilar biliary obstruction. Segmental cholangitis is defined as a high-grade fever (> 38°C) which continues longer than 24 hours with inhomogeneous parenchymal enhancement in an undrained segment during the hepatic arterial phase on the contrast-enhanced computed tomography or deteriorated dilation of an undrained branch.13

Application of the TOKYO Criteria to Reporting of Outcomes of EUS-guided Biliary Drainage

EUS-guided biliary drainage, including choledochoduodenostomy, hepaticogastrostomy, and antegrade transpapillary stent placement, is increasingly utilized as an alternative to ERCP for cases where endoscopic approach to the biliary system is difficult or impossible.6268 Although the TOKYO criteria were originally proposed as guidelines for evaluation of biliary stents placed via the transpapillary route, these criteria can be readily applied for evaluation of outcomes of EUS-guided biliary drainage. Using the TOKYO criteria, TRBO, causes of RBO, and functional success can be similarly assessed for EUS-guided biliary drainage. Due to the nature of the procedure, technical success can be defined as successful placement of a stent in the intended location, whether a stent covers the stricture or not. In patients receiving EUS-guided biliary drainage for segmental cholangitis or cholecystitis, stent dysfunction, which is also defined as a composite endpoint of either occlusion or migration, can be used as the primary outcome. Here, stent occlusion is defined as presence of elevated inflammatory markers as compared with baseline values along with biliary dilation on imaging studies, or endoscopic findings suggesting it. Stent migration is defined as presence of endoscopic findings of a completely or partially migrated stent at the time of a reintervention for patients with stent dysfunction. The TOKYO criteria have documented the definitions and severity of adverse events that are observed both for transpapillary and EUS-guided placement of biliary stents, including pancreatitis, cholangitis, cholecystitis, bleeding, and perforation.44 A potential modification to the list of adverse events is to include bile leakage as an adverse event specific for EUS-guided biliary drainage (Table 1).44 Bile leakage is defined as extravasation of bile suggested by contact during the procedure or abdominal bile collection demonstrated by imaging studies and/or an elevated level of bilirubin in abdominal fluids after the procedure. Pancreatitis is less commonly observed compared with biliary stent placement via ERCP. In studies of EUS-guided biliary drainage, it is also mandatory to report procedural characteristics (e.g., puncture route, use of the rendezvous technique, combined use of transpapillary and transmural stents), but this discussion is beyond the scope of this article.

Conclusions

In this review, we overviewed the TOKYO criteria as a standardized reporting system for outcomes of endoscopic biliary stents and discussed potential challenges in application of the criteria in clinical practice. The TOKYO criteria can be utilized irrespective of cause of biliary obstruction (benign vs malignant), location of biliary obstruction (distal vs hilar),95,96 and types of stents (e.g., plastic vs metal, uncovered vs covered SEMS). These guidelines can be also utilized for evaluation of biliary stents placed via ERCP assisted by a single- or double-balloon endoscope for patients with altered gastrointestinal anatomy (e.g., Billroth II, Roux-en-Y gastrojejunostomy).97100 Therefore, if combined with the STROBE or CONSORT checklist, the TOKYO criteria would help us to report the outcomes associated with a variety of ERCP-based stent placement procedures in a standardized manner. Standardizing the terminology and methodology for reporting study results would also facilitate the design of clinical studies. More importantly, a standardized reporting system would help readers of a published study to interpret the results appropriately and compare the findings between different studies. Given growing popularity of EUS-guided biliary drainage, the application of the TOKYO criteria to evaluation of the outcomes of this endoscopic procedure may be considered. Finally, the TOKYO criteria would support recent trends in use of individual patient data and data sharing for integration of the results of studies across different institutions and nations.

Conflicts of Interest

No potential conflict of interest relevant to this article was reported.

Figures
Fig. 1. The TOKYO criteria for reporting of short- and long-term outcomes of endoscopic placement of biliary stents. RBO, recurrent biliary obstruction.
Fig. 2. The TOKYO criteria for reporting of recurrent biliary obstruction (RBO) after endoscopic placement of biliary stents..
Fig. 3. The TOKYO criteria for reporting of adverse events associated with endoscopic placement of biliary stents.
Tables

Table 1

Severity Grading of Adverse Events Associated with Endoscopic Ultrasound-guided Biliary Drainage

Adverse eventSeverity

MildModerateSevere
Bile leakagePossible or only slight leak of bile or contrast, requiring treatment for ≤ 3 daysDefinite bile leakage treated for 4–10 daysTreatment for > 10 days or an intervention (endoscopic, percutaneous, or surgical)
Pancreatitis*Hospitalization for ≤ 3 daysHospitalization for 4–10 days or any of the following: requirement of stent removal, organ failure lasting ≤ 48 hours, or local or systemic complications without persistent organ failureHospitalization for > 10 days
Cholangitis*Antibiotics onlyFebrile or septic illness requiring hospitalization for 4–10 days or an intervention (endoscopic or percutaneous)Hospitalization for > 10 days, septic shock, or organ failure
Cholecystitis*Conservative management onlyHospitalization for 4–10 days or an intervention (endoscopic, percutaneous, or surgical) including stent removalHospitalization for > 10 days, septic shock, or organ failure
Bleeding*No transfusionTransfusion of ≤ 4 units without an angiographic or surgical interventionTransfusion of ≥ 5 units or an intervention (angiographic or surgical)
Perforation of the gastrointestinal tract*Possible or only slight leak of fluid or contrast, treated by fluids and suction for ≤ 3 daysDefinite perforation treated for 4–10 days or an intervention (endoscopic or percutaneous)Hospitalization for > 10 days or an surgery
OtherConservative management onlyHospitalization for 4–10 daysHospitalization for > 10 days or an intervention (endoscopic, percutaneous, or surgical)

*Severity of these adverse events has been defined similarly as that of adverse events associated with transpapillary placement of biliary stents in the TOKYO criteria.44

Hospitalization or prolonged hospitalization.

Excluding additional placement of a biliary stent or nasobiliary catheter during the same session as endoscopic ultrasound-guided biliary drainage.

References
  1. Kirkham, JJ, Dwan, KM, Altman, DG, Gamble, C, Dodd, S, and Smyth, R (2010). The impact of outcome reporting bias in randomised controlled trials on a cohort of systematic reviews. BMJ. 340, c365.
    Pubmed CrossRef
  2. von Elm, E, Altman, DG, Egger, M, Pocock, SJ, Gøtzsche, PC, Vandenbroucke, JP, and STROBE Initiative (2007). The strengthening the reporting of observational studies in Epidemiology (STROBE) statement: guidelines for reporting observational studies. Lancet. 370, 1453-7.
    Pubmed CrossRef
  3. Schulz, KF, Altman, DG, Moher, D, and CONSORT Group (2010). CONSORT 2010 statement: updated guidelines for reporting parallel group randomised trials. BMJ. 340, c332.
    Pubmed KoreaMed CrossRef
  4. Moher, D, Liberati, A, Tetzlaff, J, Altman, DG, and PRISMA Group (2009). Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement. Ann Intern Med. 151, Array-9.
    Pubmed CrossRef
  5. Krishnamoorthi, R, Jayaraj, M, and Kozarek, R (2017). Endoscopic stents for the biliary tree and pancreas. Curr Treat Options Gastroenterol. 15, 397-415.
    Pubmed CrossRef
  6. Tsuchiya, T, Sofuni, A, Tsuji, S, Mukai, S, Matsunami, Y, and Nagakawa, Y (2017). Endoscopic management of acute cholangitis according to the TG13. Dig Endosc. 29, 94-9.
    Pubmed CrossRef
  7. Isayama, H, Yasuda, I, and Tan, D (2017). Current strategies for endoscopic management of acute cholangitis. Dig Endosc. 29, 70-7.
    Pubmed CrossRef
  8. Zorrón Pu, L, de Moura, EG, Bernardo, WM, Baracat, FI, Mendonça, EQ, and Kondo, A (2015). Endoscopic stenting for inoperable malignant biliary obstruction: a systematic review and meta-analysis. World J Gastroenterol. 21, 13374-85.
    Pubmed KoreaMed CrossRef
  9. Almadi, MA, Barkun, JS, and Barkun, AN (2015). Stenting in malignant biliary obstruction. Gastrointest Endosc Clin N Am. 25, 691-711.
    Pubmed CrossRef
  10. Baron, TH (2014). Best endoscopic stents for the biliary tree and pancreas. Curr Opin Gastroenterol. 30, 453-6.
    Pubmed CrossRef
  11. Walter, D, van Boeckel, PG, Groenen, MJ, Weusten, BL, Witteman, BJ, and Tan, G (2015). Cost efficacy of metal stents for palliation of extrahepatic bile duct obstruction in a randomized controlled trial. Gastroenterology. 149, 130-8.
    Pubmed CrossRef
  12. Barkun, AN, Adam, V, Martel, M, AlNaamani, K, and Moses, PL (2015). Partially covered self-expandable metal stents versus polyethylene stents for malignant biliary obstruction: a cost-effectiveness analysis. Can J Gastroenterol Hepatol. 29, 377-83.
    Pubmed KoreaMed CrossRef
  13. Kiriyama, S, Takada, T, Strasberg, SM, Solomkin, JS, Mayumi, T, and Pitt, HA (2013). TG13 guidelines for diagnosis and severity grading of acute cholangitis (with videos). J Hepatobiliary Pancreat Sci. 20, 24-34.
    Pubmed CrossRef
  14. Isayama, H, Komatsu, Y, Tsujino, T, Sasahira, N, Hirano, K, and Toda, N (2004). A prospective randomised study of “covered” versus “uncovered” diamond stents for the management of distal malignant biliary obstruction. Gut. 53, 729-34.
    Pubmed KoreaMed CrossRef
  15. Krokidis, M, Fanelli, F, Orgera, G, Bezzi, M, Passariello, R, and Hatzidakis, A (2010). Percutaneous treatment of malignant jaundice due to extrahepatic cholangiocarcinoma: covered Viabil stent versus uncovered Wallstents. Cardiovasc Intervent Radiol. 33, 97-106.
    CrossRef
  16. Kullman, E, Frozanpor, F, Söderlund, C, Linder, S, Sandström, P, and Lindhoff-Larsson, A (2010). Covered versus uncovered self-expandable nitinol stents in the palliative treatment of malignant distal biliary obstruction: results from a randomized, multicenter study. Gastrointest Endosc. 72, 915-23.
    Pubmed CrossRef
  17. Telford, JJ, Carr-Locke, DL, Baron, TH, Poneros, JM, Bounds, BC, and Kelsey, PB (2010). A randomized trial comparing uncovered and partially covered self-expandable metal stents in the palliation of distal malignant biliary obstruction. Gastrointest Endosc. 72, 907-14.
    Pubmed CrossRef
  18. Krokidis, M, Fanelli, F, Orgera, G, Tsetis, D, Mouzas, I, and Bezzi, M (2011). Percutaneous palliation of pancreatic head cancer: randomized comparison of ePTFE/FEP-covered versus uncovered nitinol biliary stents. Cardiovasc Intervent Radiol. 34, 352-61.
    CrossRef
  19. Ung, KA, Stotzer, PO, Nilsson, A, Gustavsson, ML, and Johnsson, E (2013). Covered and uncovered self-expandable metallic Hanarostents are equally efficacious in the drainage of extrahepatic malignant strictures. Results of a double-blind randomized study. Scand J Gastroenterol. 48, 459-65.
    Pubmed CrossRef
  20. Kitano, M, Yamashita, Y, Tanaka, K, Konishi, H, Yazumi, S, and Nakai, Y (2013). Covered self-expandable metal stents with an anti-migration system improve patency duration without increased complications compared with uncovered stents for distal biliary obstruction caused by pancreatic carcinoma: a randomized multicenter trial. Am J Gastroenterol. 108, 1713-22.
    Pubmed CrossRef
  21. Yang, MJ, Kim, JH, Yoo, BM, Hwang, JC, Yoo, JH, and Lee, KS (2015). Partially covered versus uncovered self-expandable nitinol stents with anti-migration properties for the palliation of malignant distal biliary obstruction: a randomized controlled trial. Scand J Gastroenterol. 50, 1490-9.
    Pubmed CrossRef
  22. Davids, PH, Groen, AK, Rauws, EA, Tytgat, GN, and Huibregtse, K (1992). Randomised trial of self-expanding metal stents versus polyethylene stents for distal malignant biliary obstruction. Lancet. 340, 1488-92.
    Pubmed CrossRef
  23. Knyrim, K, Wagner, HJ, Pausch, J, and Vakil, N (1993). A prospective, randomized, controlled trial of metal stents for malignant obstruction of the common bile duct. Endoscopy. 25, 207-12.
    Pubmed CrossRef
  24. Wagner, HJ, Knyrim, K, Vakil, N, and Klose, KJ (1993). Plastic endoprostheses versus metal stents in the palliative treatment of malignant hilar biliary obstruction. A prospective and randomized trial. Endoscopy. 25, 213-8.
    Pubmed CrossRef
  25. Lammer, J, Hausegger, KA, Flückiger, F, Winkelbauer, FW, Wildling, R, and Klein, GE (1996). Common bile duct obstruction due to malignancy: treatment with plastic versus metal stents. Radiology. 201, 167-72.
    Pubmed CrossRef
  26. Travis, S, and Nicholson, T (1997). Palliation of unresectable pancreatic malignant biliary obstruction: results of a randomized trial comparing percutaneously placed metal and plastic endoprostheses. J Interv Radiol. 12, 17-21.
  27. Prat, F, Chapat, O, Ducot, B, Ponchon, T, Pelletier, G, and Fritsch, J (1998). A randomized trial of endoscopic drainage methods for inoperable malignant strictures of the common bile duct. Gastrointest Endosc. 47, 1-7.
    Pubmed CrossRef
  28. Piñol, V, Castells, A, Bordas, JM, Real, MI, Llach, J, and Montañà, X (2002). Percutaneous self-expanding metal stents versus endoscopic polyethylene endoprostheses for treating malignant biliary obstruction: randomized clinical trial. Radiology. 225, 27-34.
    Pubmed CrossRef
  29. Kaassis, M, Boyer, J, Dumas, R, Ponchon, T, Coumaros, D, and Delcenserie, R (2003). Plastic or metal stents for malignant stricture of the common bile duct? Results of a randomized prospective study. Gastrointest Endosc. 57, 178-82.
    Pubmed CrossRef
  30. Katsinelos, P, Paikos, D, Kountouras, J, Chatzimavroudis, G, Paroutoglou, G, and Moschos, I (2006). Tannenbaum and metal stents in the palliative treatment of malignant distal bile duct obstruction: a comparative study of patency and cost effectiveness. Surg Endosc. 20, 1587-93.
    Pubmed CrossRef
  31. Soderlund, C, and Linder, S (2006). Covered metal versus plastic stents for malignant common bile duct stenosis: a prospective, randomized, controlled trial. Gastrointest Endosc. 63, 986-95.
    Pubmed CrossRef
  32. Isayama, H, Yasuda, I, Ryozawa, S, Maguchi, H, Igarashi, Y, and Matsuyama, Y (2011). Results of a Japanese multicenter, randomized trial of endoscopic stenting for non-resectable pancreatic head cancer (JM-test): covered Wallstent versus DoubleLayer stent. Dig Endosc. 23, 310-5.
    Pubmed CrossRef
  33. Sangchan, A, Kongkasame, W, Pugkhem, A, Jenwitheesuk, K, and Mairiang, P (2012). Efficacy of metal and plastic stents in unresectable complex hilar cholangiocarcinoma: a randomized controlled trial. Gastrointest Endosc. 76, 93-9.
    Pubmed CrossRef
  34. Moses, PL, Alnaamani, KM, Barkun, AN, Gordon, SR, Mitty, RD, and Branch, MS (2013). Randomized trial in malignant biliary obstruction: plastic vs partially covered metal stents. World J Gastroenterol. 19, 8638-46.
    KoreaMed CrossRef
  35. Mukai, T, Yasuda, I, Nakashima, M, Doi, S, Iwashita, T, and Iwata, K (2013). Metallic stents are more efficacious than plastic stents in unresectable malignant hilar biliary strictures: a randomized controlled trial. J Hepatobiliary Pancreat Sci. 20, 214-22.
    CrossRef
  36. Schmidt, A, Riecken, B, Rische, S, Klinger, C, Jakobs, R, and Bechtler, M (2015). Wing-shaped plastic stents vs. self-expandable metal stents for palliative drainage of malignant distal biliary obstruction: a randomized multicenter study. Endoscopy. 47, 430-6.
    Pubmed CrossRef
  37. Hamada, T, Hakuta, R, Nakai, Y, Isayama, H, and Koike, K (2017). Lack in standardized reporting of biliary stents: a meta-analysis complicated by the inconsistency. Am J Gastroenterol. 112, 809-10.
    Pubmed CrossRef
  38. Almadi, MA, Barkun, A, and Martel, M (2017). Plastic vs. self-expandable metal stents for palliation in malignant biliary obstruction: a series of meta-analyses. Am J Gastroenterol. 112, 260-73.
    CrossRef
  39. Hamada, T, Nakai, Y, and Isayama, H (2013). Two meta-analyses with different conclusions: stent outcomes should be standardized before their integration. Clin Gastroenterol Hepatol. 11, 748.
    Pubmed CrossRef
  40. Almadi, MA, Barkun, AN, and Martel, M (2013). No benefit of covered vs uncovered self-expandable metal stents in patients with malignant distal biliary obstruction: a meta-analysis. Clin Gastroenterol Hepatol. 11, 27-37.e1.
    CrossRef
  41. Saleem, A, Leggett, CL, Murad, MH, and Baron, TH (2011). Meta-analysis of randomized trials comparing the patency of covered and uncovered self-expandable metal stents for palliation of distal malignant bile duct obstruction. Gastrointest Endosc. 74, 321-7.e1–3.
    Pubmed CrossRef
  42. Tringali, A, Hassan, C, Rota, M, Rossi, M, Mutignani, M, and Aabakken, L (2018). Covered vs. uncovered self-expandable metal stents for malignant distal biliary strictures: a systematic review and meta-analysis. Endoscopy. 50, 631-41.
    Pubmed CrossRef
  43. Parmar, MK, Torri, V, and Stewart, L (1998). Extracting summary statistics to perform meta-analyses of the published literature for survival endpoints. Stat Med. 17, 2815-34.
    CrossRef
  44. Isayama, H, Hamada, T, Yasuda, I, Itoi, T, Ryozawa, S, and Nakai, Y (2015). TOKYO criteria 2014 for transpapillary biliary stenting. Dig Endosc. 27, 259-64.
    CrossRef
  45. Morita, S, Arai, Y, Sugawara, S, Sone, M, Sakamoto, Y, and Okusaka, T (2018). Antireflux metal stent for initial treatment of malignant distal biliary obstruction. Gastroenterology Res Pract. 2018, 3805173.
  46. Hamada, T, Nakai, Y, Lau, JY, Moon, JH, Hayashi, T, and Yasuda, I (2018). International study of endoscopic management of distal malignant biliary obstruction combined with duodenal obstruction. Scand J Gastroenterol. 53, 46-55.
    CrossRef
  47. Kogure, H, Ryozawa, S, Maetani, I, Nakai, Y, Kawakami, H, and Yasuda, I (2017). A prospective multicenter study of a fully covered metal stent in patients with distal malignant biliary obstruction: WATCH-2 study. Dig Dis Sci.
    Pubmed CrossRef
  48. Iwashita, T, Yasuda, I, Mukai, T, Iwata, K, Doi, S, and Uemura, S (2017). Endoscopic ultrasound-guided antegrade biliary stenting for unresectable malignant biliary obstruction in patients with surgically altered anatomy: single-center prospective pilot study. Dig Endosc. 29, 362-8.
    Pubmed CrossRef
  49. Yokota, Y, Fukasawa, M, Takano, S, Kadokura, M, Shindo, H, and Takahashi, E (2017). Partially covered metal stents have longer patency than uncovered and fully covered metal stents in the management of distal malignant biliary obstruction: a retrospective study. BMC Gastroenterol. 17, 105.
    Pubmed KoreaMed CrossRef
  50. Cui, W, Wang, Y, Fan, W, Lu, M, Zhang, Y, and Yao, W (2017). Comparison of intraluminal radiofrequency ablation and stents vs. stents alone in the management of malignant biliary obstruction. Int J Hyperthermia. 33, 853-61.
    Pubmed
  51. Cui, W, Fan, W, Lu, M, Zhang, Y, Yao, W, and Li, J (2017). The safety and efficacy of percutaneous intraductal radiofrequency ablation in unresectable malignant biliary obstruction: a single-institution experience. BMC Cancer. 17, 288.
    Pubmed KoreaMed CrossRef
  52. Sogabe, Y, Kodama, Y, Honjo, H, Aoyama, I, Muramoto, Y, and Koga, E (2018). Tumor invasion to the arteries feeding the gallbladder as a novel risk factor for cholecystitis after metallic stent placement in distal malignant biliary obstruction. Dig Endosc. 30, 380-7.
    CrossRef
  53. Jang, SI, Lee, SJ, Jeong, S, Lee, DH, Kim, MH, and Yoon, HJ (2017). Efficacy of a multiplex paclitaxel emission stent using a Pluronic¢ç mixture membrane versus a covered metal stent in malignant biliary obstruction: a prospective randomized comparative study. Gut Liver. 11, 567-73.
    Pubmed KoreaMed CrossRef
  54. Inoue, T, Ishii, N, Kobayashi, Y, Kitano, R, Sakamoto, K, and Ohashi, T (2017). Simultaneous versus sequential side-by-side bilateral metal stent placement for malignant hilar biliary obstructions. Dig Dis Sci. 62, 2542-9.
    Pubmed CrossRef
  55. Inoue, T, Naitoh, I, Okumura, F, Ozeki, T, Anbe, K, and Iwasaki, H (2016). Reintervention for stent occlusion after bilateral self-expandable metallic stent placement for malignant hilar biliary obstruction. Dig Endosc. 28, 731-7.
    Pubmed CrossRef
  56. Yamauchi, H, Kida, M, Okuwaki, K, Miyazawa, S, Iwai, T, and Imaizumi, H (2016). A case series: outcomes of endoscopic biliary self-expandable metal stent for malignant biliary obstruction with surgically altered anatomy. Dig Dis Sci. 61, 2436-41.
    Pubmed CrossRef
  57. Mukai, T, Yasuda, I, Isayama, H, Iwashita, T, Itoi, T, and Kawakami, H (2016). Pilot study of a novel, large-bore, fully covered self-expandable metallic stent for unresectable distal biliary malignancies. Dig Endosc. 28, 671-9.
    Pubmed CrossRef
  58. Budzyńska, A, Nowakowska-Duława, E, Marek, T, and Hartleb, M (2016). Comparison of patency and cost-effectiveness of self-expandable metal and plastic stents used for malignant biliary strictures: a Polish single-center study. Eur J Gastroenterol Hepatol. 28, 1223-8.
    CrossRef
  59. Inoue, T, Okumura, F, Naitoh, I, Fukusada, S, Kachi, K, and Ozeki, T (2016). Feasibility of the placement of a novel 6-mm diameter threaded fully covered self-expandable metal stent for malignant hilar biliary obstructions (with videos). Gastrointest Endosc. 84, 352-7.
    Pubmed CrossRef
  60. Park, JM, Lee, SH, Chung, KH, Jang, DK, Ryu, JK, and Kim, YT (2016). Endoscopic bilateral stent-in-stent placement for malignant hilar obstruction using a large cell type stent. Hepatobiliary Pancreat Dis Int. 15, 633-9.
    Pubmed CrossRef
  61. Naitoh, I, Nakazawa, T, Ban, T, Okumura, F, Hirano, A, and Takada, H (2015). 8-mm versus 10-mm diameter self-expandable metallic stent in bilateral endoscopic stent-in-stent deployment for malignant hilar biliary obstruction. J Hepatobiliary Pancreat Sci. 22, 396-401.
    Pubmed CrossRef
  62. Dhir, V, Isayama, H, Itoi, T, Almadi, M, Siripun, A, and Teoh, AYB (2017). Endoscopic ultrasonography-guided biliary and pancreatic duct interventions. Dig Endosc. 29, 472-85.
    Pubmed CrossRef
  63. Nakai, Y, Isayama, H, Yamamoto, N, Matsubara, S, Kogure, H, and Mizuno, S (2017). Indications for endoscopic ultrasonography (EUS)-guided biliary intervention: does EUS always come after failed endoscopic retrograde cholangiopancreatography?. Dig Endosc. 29, 218-25.
    CrossRef
  64. Hara, K, Yamao, K, Mizuno, N, Hijioka, S, Imaoka, H, and Tajika, M (2016). Endoscopic ultrasonography-guided biliary drainage: who, when, which, and how?. World J Gastroenterol. 22, 1297-303.
    Pubmed KoreaMed CrossRef
  65. Tyberg, A, Desai, AP, Kumta, NA, Brown, E, Gaidhane, M, and Sharaiha, RZ (2016). EUS-guided biliary drainage after failed ERCP: a novel algorithm individualized based on patient anatomy. Gastrointest Endosc. 84, 941-6.
    Pubmed CrossRef
  66. Kawakubo, K, Kawakami, H, Kuwatani, M, Kubota, Y, Kawahata, S, and Kubo, K (2016). Endoscopic ultrasound-guided choledochoduodenostomy vs. transpapillary stenting for distal biliary obstruction. Endoscopy. 48, 164-9.
  67. Khashab, MA, Levy, MJ, Itoi, T, and Artifon, EL (2015). EUS-guided biliary drainage. Gastrointest Endosc. 82, 993-1001.
    Pubmed CrossRef
  68. Hamada, T, Isayama, H, Nakai, Y, Kogure, H, Yamamoto, N, and Kawakubo, K (2014). Transmural biliary drainage can be an alternative to transpapillary drainage in patients with an indwelling duodenal stent. Dig Dis Sci. 59, 1931-8.
    Pubmed CrossRef
  69. Hamada, T, Isayama, H, Nakai, Y, Kogure, H, Yamamoto, N, and Koike, K (2014). Tips and troubleshooting for transpapillary metal stenting for distal malignant biliary obstruction. J Hepatobiliary Pancreat Sci. 21, E12-8.
    Pubmed CrossRef
  70. Moon, SH, Kim, MH, Park, DH, Song, TJ, Eum, J, and Lee, SS (2010). Modified fully covered self-expandable metal stents with antimigration features for benign pancreatic-duct strictures in advanced chronic pancreatitis, with a focus on the safety profile and reducing migration. Gastrointest Endosc. 72, 86-91.
    Pubmed CrossRef
  71. Martins, FP, De Paulo, GA, Contini, MLC, and Ferrari, AP (2018). Metal versus plastic stents for anastomotic biliary strictures after liver transplantation: a randomized controlled trial. Gastrointest Endosc. 87, 131.e1–13.
    CrossRef
  72. Coté, GA, Slivka, A, Tarnasky, P, Mullady, DK, Elmunzer, BJ, and Elta, G (2016). Effect of covered metallic stents compared with plastic stents on benign biliary stricture resolution: a randomized clinical trial. JAMA. 315, 1250-7.
    Pubmed KoreaMed CrossRef
  73. Wen, F, Lu, Z, Mao, X, Liang, H, and Guo, Q (2013). Bridging across the ampulla with metal stents: evidences for intestinal bile reflux. Hepatogastroenterology. 60, 1903-5.
  74. Misra, SP, and Dwivedi, M (2009). Reflux of duodenal contents and cholangitis in patients undergoing self-expanding metal stent placement. Gastrointest Endosc. 70, 317-21.
    Pubmed CrossRef
  75. Okamoto, T, Fujioka, S, Yanagisawa, S, Yanaga, K, Kakutani, H, and Tajiri, H (2006). Placement of a metallic stent across the main duodenal papilla may predispose to cholangitis. Gastrointest Endosc. 63, 792-6.
    Pubmed CrossRef
  76. Isayama, H, Nakai, Y, Toyokawa, Y, Togawa, O, Gon, C, and Ito, Y (2009). Measurement of radial and axial forces of biliary self-expandable metallic stents. Gastrointest Endosc. 70, 37-44.
    Pubmed CrossRef
  77. Isayama, H, Nakai, Y, Hamada, T, Matsubara, S, Kogure, H, and Koike, K (2016). Understanding the mechanical forces of self-expandable metal stents in the biliary ducts. Curr Gastroenterol Rep. 18, 64.
    Pubmed CrossRef
  78. Nakai, Y, Isayama, H, Kogure, H, Hamada, T, Togawa, O, and Ito, Y (2014). Risk factors for covered metallic stent migration in patients with distal malignant biliary obstruction due to pancreatic cancer. J Gastroenterol Hepatol. 29, 1744-9.
    Pubmed CrossRef
  79. Hamada, T, Nakai, Y, Isayama, H, Sasaki, T, Kogure, H, and Kawakubo, K (2013). Duodenal metal stent placement is a risk factor for biliary metal stent dysfunction: an analysis using a time-dependent covariate. Surg Endosc. 27, 1243-8.
    CrossRef
  80. Hamada, T, Isayama, H, Nakai, Y, Togawa, O, Kogure, H, and Kawakubo, K (2011). Duodenal invasion is a risk factor for the early dysfunction of biliary metal stents in unresectable pancreatic cancer. Gastrointest Endosc. 74, 548-55.
    Pubmed CrossRef
  81. Hamada, T, Isayama, H, Nakai, Y, Togawa, O, Takahara, N, and Uchino, R (2017). Antireflux metal stent as a first-line metal stent for distal malignant biliary obstruction: a pilot study. Gut Liver. 11, 142-8.
    KoreaMed CrossRef
  82. Lee, YN, Moon, JH, Choi, HJ, Choi, MH, Lee, TH, and Cha, SW (2016). Effectiveness of a newly designed antireflux valve metal stent to reduce duodenobiliary reflux in patients with unresectable distal malignant biliary obstruction: a randomized, controlled pilot study (with videos). Gastrointest Endosc. 83, 404-12.
    CrossRef
  83. Hamada, T, Isayama, H, Nakai, Y, Togawa, O, Kogure, H, and Takahara, N (2015). Antireflux metal stent with an antimigration system for distal malignant biliary obstruction: a feasibility pilot study. Surg Laparosc Endosc Percutan Tech. 25, 212-7.
    Pubmed CrossRef
  84. Hu, B, Wang, TT, Wu, J, Shi, ZM, Gao, DJ, and Pan, YM (2014). Antireflux stents to reduce the risk of cholangitis in patients with malignant biliary strictures: a randomized trial. Endoscopy. 46, 120-6.
    Pubmed CrossRef
  85. Tai, BC, Grundy, RG, and Machin, D (2010). On the importance of accounting for competing risks in pediatric cancer trials designed to delay or avoid radiotherapy: I. basic concepts and first analyses. Int J Radiat Oncol Biol Phys. 76, 1493-9.
    CrossRef
  86. Tai, BC, Machin, D, White, I, Gebski, V, and EOI (The European Osteosarcoma Intergroup) (2001). Competing risks analysis of patients with osteosarcoma: a comparison of four different approaches. Stat Med. 20, 661-84.
    Pubmed CrossRef
  87. Hamada, T, Nakai, Y, Isayama, H, Togawa, O, Kogure, H, and Kawakubo, K (2014). Estimation and comparison of cumulative incidences of biliary self-expandable metallic stent dysfunction accounting for competing risks. Dig Endosc. 26, 270-5.
    CrossRef
  88. Nakai, Y, Isayama, H, Mukai, T, Itoi, T, Maetani, I, and Kawakami, H (2013). Impact of anti-cancer treatment on recurrent obstruction in covered metallic stents for malignant biliary obstruction. J Gastroenterol. 48, 1293-9.
    Pubmed CrossRef
  89. Eum, YO, Kim, YT, Lee, SH, Park, SW, Hwang, JH, and Yoon, WJ (2013). Stent patency using competing risk model in unresectable pancreatic cancers inserted with biliary self-expandable metallic stent. Dig Endosc. 25, 67-75.
    Pubmed CrossRef
  90. van Hooft, JE, van Montfoort, ML, Jeurnink, SM, Bruno, MJ, Dijkgraaf, MG, and Siersema, PD (2011). Safety and efficacy of a new non-foreshortening nitinol stent in malignant gastric outlet obstruction (DUONITI study): a prospective, multicenter study. Endoscopy. 43, 671-5.
    Pubmed CrossRef
  91. Law, R, and Baron, TH (2018). Endoscopic ultrasound-guided gallbladder drainage. Gastrointest Endosc Clin N Am. 28, 187-95.
    Pubmed CrossRef
  92. Kawakubo, K, Isayama, H, Nakai, Y, Togawa, O, Sasahira, N, and Kogure, H (2012). Risk factors for pancreatitis following transpapillary self-expandable metal stent placement. Surg Endosc. 26, 771-6.
    CrossRef
  93. Cotton, PB, Lehman, G, Vennes, J, Geenen, JE, Russell, RC, and Meyers, WC (1991). Endoscopic sphincterotomy complications and their management: an attempt at consensus. Gastrointest Endosc. 37, 383-93.
    Pubmed CrossRef
  94. Cotton, PB, Eisen, GM, Aabakken, L, Baron, TH, Hutter, MM, and Jacobson, BC (2010). A lexicon for endoscopic adverse events: report of an ASGE workshop. Gastrointest Endosc. 71, 446-54.
    Pubmed CrossRef
  95. Kogure, H, Isayama, H, Nakai, Y, Tsujino, T, Matsubara, S, and Yashima, Y (2014). High single-session success rate of endoscopic bilateral stent-in-stent placement with modified large cell Niti-S stents for malignant hilar biliary obstruction. Dig Endosc. 26, 93-9.
    CrossRef
  96. Naitoh, I, Hayashi, K, Nakazawa, T, Okumura, F, Miyabe, K, and Shimizu, S (2012). Side-by-side versus stent-in-stent deployment in bilateral endoscopic metal stenting for malignant hilar biliary obstruction. Dig Dis Sci. 57, 3279-85.
    Pubmed CrossRef
  97. Shimatani, M, Tokuhara, M, Kato, K, Miyamoto, S, Masuda, M, and Sakao, M (2017). Utility of newly developed short-type double-balloon endoscopy for endoscopic retrograde cholangiography in postoperative patients. J Gastroenterol Hepatol. 32, 1348-54.
    CrossRef
  98. Yane, K, Katanuma, A, Maguchi, H, Takahashi, K, Kin, T, and Ikarashi, S (2017). Short-type single-balloon enteroscope-assisted ERCP in postsurgical altered anatomy: potential factors affecting procedural failure. Endoscopy. 49, 69-74.
  99. De Koning, M, and Moreels, TG (2016). Comparison of double-balloon and single-balloon enteroscope for therapeutic endoscopic retrograde cholangiography after Roux-en-Y small bowel surgery. BMC Gastroenterol. 16, 98.
    Pubmed KoreaMed CrossRef
  100. Kogure, H, Tsujino, T, Isayama, H, Takahara, N, Uchino, R, and Hamada, T (2014). Short- and long-term outcomes of endoscopic papillary large balloon dilation with or without sphincterotomy for removal of large bile duct stones. Scand J Gastroenterol. 49, 121-8.
    CrossRef


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