Factors prolonging self-expandable metal stent patency in patients with malignant distal biliary obstruction: a multicenter retrospective study

Objective: Various self-expandable metal stent (SEMS) types and placement methods have been developed to improve stent patency in patients with malignant distal biliary obstruction. This retrospective study aimed to evaluate factors contributing to prolonged stent patency.
Methods: Factors affecting time to recurrent biliary obstruction (TRBO) including patient backgrounds and SEMS types (covered, anti-reflux, laser-cut; length, bore size) and placement methods were analyzed using Cox proportional hazards model. Further, selection bias was reduced using propensity score matching (PSM) for all factors.
Results: Between 2010 and 2021, 469 patients met the inclusion criteria. Multivariate analysis showed that 8-cm length (hazard ratio [HR]=1.48, P=0.02), 12-mm bore (HR=0.59, P<0.01), and laser-cut type (HR=0.31, P<0.01) were stent characteristics independently associated with prolonged TRBO. Because SEMS length was selected according to patient condition, effects of 12-mm-bore and laser-cut SEMS use were evaluated after PSM. Thirty patients with laser-cut and braided stents and 116 patients with 12- and 10-mm-bore stents were compared. HRs for 12-mm-bore and laser-cut SEMS use were 0.49 (P<0.01) and 0.15 (P<0.01), respectively.
Conclusions: Stent characteristics independently associated with prolonged TRBO were 12-mm bore and laser-cut type. Therefore, stent occlusion and migration could be reduced using 12-mm-bore and laser-cut SEMSs, respectively.