Covered and Uncovered Self-Expandable Metallic Stents in the Treatment of Malignant Biliary Obstruction

Context: Self-expandable metal stents (SEMSs) are commonly used in the treatment of malignant biliary obstruction. We performed a meta-analysis to compare the efficacy of covered self-expandable metallic stents (CSEMSs) and uncovered self-expandable metallic stents (UCSEMSs) for patients with malignant distal biliary obstruction. Methods: A comprehensive search was conducted using PubMed, Embase, Cochrane, and CNKI databases from 2010 to 2019. All randomized controlled trials, which compared the use of the CSEMSs and UCSEMSs for the treatment of malignant distal biliary obstruction were included in this study. Results: This meta-analysis included 1,539 patients enrolled in 13 trials. There was no difference between the two groups in terms of patients' survival (hazard ratio (HR) 0.96, 95% confidence interval (CI): 0.87 - 1.07; I-2 = 32.6%), stent patency (HR 0.92, 95% CI: 0.69 - 1.22; I-2 = 56.3%), and the overall complication rate (relative risks (RR) 1.35, 95% CI: 0.82 - 2.23; I-2 = 0%). In particular, the CSEMSs group presented a lower rate of tumor ingrowth (RR 0.30, 95% CI: 0.15 - 0.57; I-2 = 58.5%) than the UCSEMSs group. However, the CSEMSs group exhibited a higher rate of tumor overgrowth (RR 1.63, 95% CI: 1.00 - 2.66; I-2 = 0%), sludge formation (RR 2.28, 95% CI: 1.36 - 3.82; I-2 = 0%), and migration (RR 5.14, 95% CI: 1.90 - 13.88; I-2 = 0%). Conclusions: Our meta-analysis indicated that there was no significant difference between the two stents, and each one had its advantages and disadvantages.