Mo1439 A Meta-Analysis Comparing the Patency of Covered and Uncovered Self-Expandable Metal Stents (SEMS) for Palliation of Distal Malignant Bile Duct Obstruction

Abstract

Self expandable metal stents (SEMS) are used for palliation of malignant biliary obstruction. We performed a meta-analysis to compare stent patency and stent survival of covered SEMS (cSEMS) and uncovered SEMS (uSEMS) in patients with unresectable, malignant, distal biliary obstruction. A comprehensive search of several databases (from each database's earliest inclusive dates to November 2010, any language, and any population) was conducted. Eligible studies for this meta-analysis were original longitudinal randomized controlled studies (RCT) that compared the clinical effectiveness of cSEMS vs. uSEMS for treatment of distal malignant biliary obstruction whether placed endoscopically or percutaneously. Outcomes of interest included stent patency, stent survival, patient survival and cause for stent dysfunction (ingrowth, overgrowth, migration and sludge formation).Working independently and in duplicate, two reviewers screened all abstracts and titles and subsequently the full text of selected references. The search identified 337 potential abstracts and titles of which 16 were retrieved in full text. Review of references identified 17 additional studies. We found 5 multicenter randomized controlled studies (RCT) containing 780 patients, which met our inclusion criteria. The median age was 66 (46% women). The median length of follow-up was 212 days. Compared to uncovered SEMS, covered SEMS were associated with significantly prolonged stent patency (WMD 60.5 days; 95% CI, 25.9, 95.2; p=0.001; I2= 0%) and longer stent survival (WMD 68.8 days; 95% CI, 25.6, 112.1; p=0.002; I2= 79%). SEMS dysfunction due to stent ingrowth was significantly lower with cSEMS (RR 0.23; 95% CI, 0.08, 0.67; p<0.01; I2 =54%). Stent migration, tumor overgrowth and sludge formation were significantly higher with cSEMS (RR 8.1; 95% CI, 1.47, 44.75; p=0.01; I2 =0%), (RR 2.02; 95% CI, 1.08, 3.78; p=0.02; I2 =0%), (RR 2.89; 95% CI, 1.27, 6.55; p=0.01; I2 =0%). 1) Despite two recent randomized trials, this meta-analysis show covered SEMS has a significantly prolonged patency than uncovered SEMS. 2) When re-obstruction (stent survival) occurs, there is a trend it is delayed when cSEMS are used. 3) Re-obstruction after cSEMS placement is more likely due to tumor overgrowth, sludge and stent migration while with uncovered SEMS is due to tumor ingrowth. Key Words:Self expandable metal stent (SEMS), Uncovered SEMS (uSEMS), Covered SEMS (cSEMS), and Randomized controlled trials (RCT).