Research Article|Articles in Press

Suprapapillary placement of plastic versus metal stents for malignant biliary hilar obstructions: A multicenter randomized trial

Published:March 10, 2023DOI:
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      Background and aims

      The efficacy of the suprapapillary placement of inside plastic stents (iPSs) for unresectable malignant hilar biliary obstructions (MHOs) has been unknown in comparison with that of inside uncovered metal stents (iMSs). This randomized controlled trial was designed to evaluate the outcomes of endoscopic placement of these stents for unresectable MHOs.


      This was an open-label, randomized study at 12 Japanese institutions. The enrolled patients with unresectable MHOs were allocated to iPS and iMS groups. The primary outcome was defined as the time to recurrent biliary obstruction (RBO) in patients for whom the intervention was both technically and clinically successful.


      Among 87 enrollments, 38 in the iPS group and 46 in the iMS group were analyzed. The technical success rates were 100% (38) and 96.6% (44/46), respectively (p = 1.00). After transferring 1 unsuccessful iMS-group patient to the iPS group, since iPSs were deployed, the clinical success rates were 90.0% (35/39) for the iPS group and 88.9% (40/45) for the iMS group from a per-protocol analysis (p = 1.00). Among the patients with clinical successes, the median times to RBO were 250 (95% confidence interval [CI], 85−415) and 361 (107−615) days, respectively (p = 0.34; log-rank test). No differences were detected in rates of adverse events.


      This phase II randomized trial did not demonstrate any statistically significant difference in stent patency between suprapapillary plastic vs. metal stents. Considering the potential advantages of plastic stents for malignant hilar obstruction, these findings suggest that suprapapillary plastic stents could represent a viable alternative to metal stents for this condition.

      Graphical abstract


      Acronyms and abbreviations:

      iPS (inside plastic stent), MHO (malignant hilar biliary obstruction), iMS (inside metal stent), RBO (recurrent biliary obstruction), ASGE (American Society for Gastrointestinal Endoscopy), TB (total biliarubin), IOC (intervention of concern), ERCP (endoscopic retrograde cholangiopancreatography), EST (endoscopic sphincterotomy), SIS (stent-in-stent), SBS (side-by-side), TRBO (time to recurrent biliary obstruction), SD (standard deviations), PTBD (percutaneous transhepatic biliary drainage), EUS-BD (EUS-guided biliary drainage)
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