S1056 Stent-in-Stent vs Side-by-Side Metal Stent Placement for Malignant Hilar Biliary Obstruction; A Meta-Analysis of Comparative Evidence

Introduction: Biliary self-expanding metal stents (SEMS) are the standard of care for the management of malignant hilar biliary obstruction. Multiple endoscopic techniques have been developed for SEMS insertion for hilar obstruction, but the clinical utility of these modalities is not well-studied. Methods: A comprehensive literature search was performed of Medline and Embase to identify studies comparing the safety and efficacy SIS and SBS SEMS insertion for malignant hilar biliary obstruction. A comparative meta-analysis with random effects model was performed for safety and efficacy endpoints of interest. Data is reported as point estimates with 95% confidence interval (CI). Results: We identified 5 studies (1 RCT, 4 retrospective studies) enrolling 127 patients in the SIS arm and 123 in the SBS arm. There was no difference in the technical success of SIS and SBS insertion (RR 0.04; -0.01,0.10; I2 0%), with no significant change in findings on influence analysis. There was no difference in functional success in relief of MBO with SIS and SBS insertion (RR 0.06; -0.05,0.17; I2 34.92%); influence analysis revealed SIS to be associated with a higher rate of functional success upon removal of one study (RR 0.12; 0.01,0.24; P = 0.028). There was no significant difference in the risk of adverse events with SIS and SBS insertion (RR -0.31; -0.75,0.13; I2 48.05%), with no significant change in findings on influence analysis. Detail analysis of the adverse effect profile revealed no significant difference in the risk of cholangitis (RR -0.15; -1.11,0.82; I 2 0%), cholecystitis (RR -0.44, -1.64,0.76; I2 0%), and tumor ingrowth/overgrowth (RR 0.21; -0.58,1.00; I2 53.53%) with SIS and SBS insertion. There was no significant difference in the risk of reintervention due to adverse events with SIS and SBS use (RR 0.21; -0.33,0.75; I2 0%). The median duration of stent patency ranged from 155-262 days and 104-253 days with SBS and SIS use, respectively. The median overall survival was 198-381 days and 159-238 days with SBS and SIS use, respectively. Conclusion: SIS and SBS SEMS insertion have a comparable technical success rate and adverse effect profile. Although not significantly different on overall pooled analysis, SIS was associated with a higher functional success rate on influence analysis, a finding that warrants further study. The duration of stent patency and overall survival are comparable with SIS and SBS use. Our findings may be utilized to design future randomized trials.Figure 1.: Through the scope suture closure of mucosal incision for peroral endoscopic myotomy (POEM) (a) Mucosal incision site (b) First tack placed inferolateral to defect, leaving a generous margin of normal mucosa (c) All four tacks are placed in a "Z" pattern around the defect (d) Defect completely closed following approximation of tacks and cinching of suture