S236 Comparison of Safety and Efficacy of Endoscopic Biliary Stents for Malignant Biliary Strictures: A Systemic Review and Meta-Analysis

Introduction: Malignant biliary obstruction can be hilar or distal depending on the etiology. Endoscopic Retrograde Cholangiopancreatography (ERCP) with stent placement is indicated in most patients prior to treatment. Plastic and uncovered metal stents (UMS) are used for hilar strictures while uncovered and covered metal stents (CMS) are used for distal strictures. Clinical practice is variable, and guidelines are still unclear with heterogenous data, especially for hilar strictures. Methods: We compared clinical efficacy and safety of biliary stents for malignant strictures. Primary outcome was time to recurrent biliary obstruction (TRBO) and secondary outcomes were technical success, clinical success, survival span (SS), need for re-intervention (NR) and complications. Pooled proportions were calculated including frequency of events over number of patients with 95% confidence limits. Random effects model by DerSimonian and Laird was used for analysis. Odds ratios (OR) were calculated by comparison of pooled proportions and P < 0.05 was considered significant. Results: Sixteen studies (6 randomized controlled trials [RCTs]) comparing plastic (n = 917) and UMS (n = 902) for hilar strictures and 16 studies (10 RCTs) comparing CMS (n = 1464) and UMS (n = 2224) for distal strictures were analyzed. For hilar strictures, UMS had significantly longer TRBO (213.12 vs 146.72 days, P < 0.0001), significantly longer survival span (261.08 vs 235.08 days, P < 0.0001) significantly lower NR (25.2% vs 43%, OR: 0.43, P < 0.0001) and significantly lower cholangitis (19% vs 6%, P = 0.02) compared to plastic. For distal strictures, comparing CMS to UMS, there was no difference in TRBO (265.51 vs 256.01 days, P = 0.13), but significantly longer SS (233.88 vs 212.27, P < 0.0001). significantly lower NR (22.1% vs 25.7%, OR: 0.69, P = 0.02) and marginally higher pancreatitis was seen (4.0% vs 3.1%, OR: 1.64, P = 0.02). Sub-group analysis for RCTs for TRBO and SS were also consistent with overall results. Other secondary outcomes were similar for hilar and distal strictures with no significant difference. Conclusion: This is the largest comprehensive meta-analysis to date combining malignant hilar and distal strictures (5507 patients). UMS offers longer TRBO with lower NR and a survival benefit for hilar strictures. CMS has lower NR and survival benefit with similar TRBO in distal strictures. Future studies should be designed considering stage of disease, survival span and cost of stents to guide clinicians to place appropriate stents.