Original article
Systematic reviews and meta-analyses
No Benefit of Covered vs Uncovered Self-Expandable Metal Stents in Patients With Malignant Distal Biliary Obstruction: A Meta-analysis

https://doi.org/10.1016/j.cgh.2012.10.019Get rights and content

Background & Aims

Self-expandable metal stents (SEMS) are used in patients with malignant distal biliary obstruction; trials that compared covered and uncovered SEMS reported different results because of heterogeneous designs and patient populations. These studies compared patency of uncovered SEMS and covered SEMS, along with rates of pancreatitis, cholecystitis, cholangitis, SEMS migration, bleeding, perforation, and recurrent biliary obstruction.

Methods

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.

Results

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.

Conclusions

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.

Section snippets

Search Strategy

A computerized medical literature search was performed by using OVID MEDLINE, EMBASE, Cochrane Library, and the ISI Web of Knowledge from 1980 to March 2012. All abstracts from Digestive Disease Week, Canadian Digestive Diseases Week, and United European Gastroenterology Week were also searched, as were clinical trials databases (http://www.clinicaltrials.gov). A highly sensitive search strategy was used to identify reports of randomized controlled trials comparing patency duration and rates of

Study Selection

From a total of 649 citations identified through the systematic review, 501 articles were excluded because they did not address the topic under study, 36 articles were reviews, 27 studies compared surgery with biliary stenting, 23 addressed preoperative stenting, 19 were related to patients with hilar biliary tumors, 12 studies compared SEMS with plastic stents, 3 were retrospective in nature, 4 studied new types of biliary stents, 3 compared 2 types of SEMS, 2 were duplicates, and 1 study was

Discussion

The use of SEMS in the management of distal malignant biliary obstruction has become common practice in cases of unresectable tumors. SEMS have the advantage of a larger inner diameter when compared with plastic biliary stents and thus a longer duration of patency, requiring fewer repeat insertions.2, 23, 24, 25, 26 Nonetheless, the use of SEMS is associated with dysfunction caused by tumor ingrowth, overgrowth, blockage by debris, and migration. Covered SEMS were introduced to prevent ingrowth

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Conflicts of interest This author discloses the following: Dr Barkun is a consultant for Boston Scientific Inc, Olympus Canada Inc, and Cook Inc and has also received “at arms-length” grant funding from both Boston Scientific Inc and Cook Inc. The remaining authors disclose no conflicts.

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