title: Covered versus uncovered self-expandable metallic stents for palliation of malignant gastric outlet obstruction: a systematic review and meta-analysis.
abstract: BACKGROUND
  Self-expandable metallic stents (SEMSs) are widely used for palliation of malignant gastric outlet obstruction (GOO). There are two types of SEMS, covered and uncovered, each with its own advantages and disadvantages. We aimed to compare the efficacy and safety between uncovered and covered SEMSs in the palliation of malignant gastric outlet obstruction.
  
  
  METHODS
  Databases including PubMed, EMBASE, the Cochrane Library, the Science Citation Index and momentous meeting abstracts were searched and evaluated by two reviewers independently.
  
  
  RESULTS
  Nine trials involving 849 patients were analyzed. Meta-analysis showed there was no significant difference in technical success rate (RR 1.0, 95% CI [0.98, 1.01]), clinical success rate (RR 1.04, 95% CI [0.98, 1.11]), post-stenting dysphagia score (WMD -0.01, 95% CI [-0.52, 0.50]), stent patency (WMD -0.31, 95% CI [-1.73, 1.11]), overall complications (RR 1.07, 95% CI [0.87, 1.32]) and reintervention rate (RR 1.30, 95% CI [0.92, 1.83]) between covered and uncovered SEMSs group. However, covered SEMSs were associated with higher migration rate (RR 3.48, 95% CI [2.16, 5.62], P < 0.00001) and lower obstruction rate (RR 0.42, 95% CI [0.24, 0.73], P = 0.002).
  
  
  CONCLUSIONS
  In the palliative treatment of malignant gastric outlet obstruction, both covered and uncovered SEMSs are safely and effective. Covered stents can reduce the risk of restenosis, whereas uncovered stents are effective in decreasing stent migration.
authors.affiliation: Department of Endoscopy, Shu-guang Hospital Affiliated to Shanghai University of Traditional Chinese Medicine, 201203 Shanghai, China. Panyamin2014@163.com.
authors.forename: Ya-min
authors.initials: YM
authors.lastname: Pan
authors.forename: Ji
authors.initials: J
authors.lastname: Pan
authors.forename: Li-kun
authors.initials: LK
authors.lastname: Guo
authors.forename: Min
authors.initials: M
authors.lastname: Qiu
authors.forename: Jia-jun
authors.initials: JJ
authors.lastname: Zhang
mesh_terms: D004867:Equipment Design; D005548:Foreign-Body Migration; D017219:Gastric Outlet Obstruction / Q000209:etiology / Q000601:surgery*; D006801:Humans; D010166:Palliative Care / Q000379:methods*; D012008:Recurrence; D012086:Reoperation; D015607:Stents / Q000009:adverse effects