We performed a meta-analysis to compare the effects of covered and uncovered SEMS in patients with malignant distal biliary obstruction. We identified randomized controlled trials by using a literature search from 1980 through March 2012. We evaluated data from 5 full articles and 4 abstracts, comprising 1061 patients, and assessed statistical heterogeneity and publication bias.
The weighted mean difference in the stent patency duration could only be calculated on the basis of 2 studies, but it was 67.9 days longer for covered SEMS than for uncovered SEMS (95 % confidence interval [CI], 60.3-75.5). A summary analysis of data from 4 trials demonstrated no differences in patency of covered vs uncovered SEMS after 6 months (odds ratio [OR], 1.82; 95 % CI, 0.62-5.25) or 12 months (OR, 1.25; 95 % CI, 0.65-2.39). There were also no differences in the rates of pancreatitis, cholecystitis, perforation, bleeding, or cholangitis; length of hospital stay; or number of recurrent biliary obstructions. However, covered SEMS had a higher migration rate (OR, 7.13; 95 % CI, 2.29-22.21). Patients with covered SEMS had a lower rate of tumor ingrowth (OR, 0.19; 95 % CI, 0.07-0.55) but a higher rate of tumor overgrowth (OR, 1.88; 95 % CI, 1.02-3.45). No summary calculations could be completed to confidently assess patient survival.
The use of covered SEMS, compared with uncovered SEMS, in patients with distal malignant biliary obstruction is of unclear benefit; covered SEMS have a higher rate of migration and do not appear to have longer patency.