Abstract
Background Self-expandable metal stents (SEMS) are used for palliation of distal malignant biliary
strictures, but the role of covered SEMS is less clear. We performed an up-to-date
meta-analysis to compare the performance of covered and uncovered SEMS in patients
with unresectable distal malignant biliary strictures.
Methods A computerized medical search was performed using MEDLINE, EMBASE, and the Cochrane
Library between 2000 and December 2016 to identify all randomized trials that compared
covered with uncovered SEMS in patients with distal malignant biliary strictures.
Primary outcomes were stent failure and patient mortality; secondary outcomes were
stent dysfunction and adverse events. Pooled estimates were computed using the random
effects model.
Results Overall, 11 RCTs involving 1272 patients were included. The primary outcomes of stent
failure and patient mortality did not differ significantly between covered and uncovered
SEMS (hazard ratio [HR] 0.68, 95 % confidence interval [CI] 0.40 – 1.17; HR 0.89,
95 %CI 0.76 – 1.05, respectively). However, stent migration and sludge formation were
much more common with covered SEMS (odds ratio [OR] 5.11, 95 %CI 1.84 – 14.17; OR
2.46, 95 %CI 1.37 – 4.43). The use of covered SEMS was associated with a lower rate
of tumor ingrowth (OR 0.21, 95 %CI 0.09 – 0.50) but a higher rate of tumor overgrowth
(OR 2.00, 95 %CI 1.15 – 3.48) compared with uncovered stents. The rates of procedure-related
adverse events were similar in both groups.
Conclusion There was a risk reduction of about 32 % for both stent failure and patient mortality
with covered SEMS but this difference was not significant. Migration and sludge rates
were higher with covered SEMS, whereas tumor ingrowth was more likely with uncovered
SEMS. The data show no added benefit of covered SEMS; further stent evolution is desirable.
