title: Covered versus uncovered metal stents for malignant gastric outlet obstruction: Systematic review and meta-analysis.
abstract: OBJECTIVE
  Self-expandable metal stents (SEMS) are used for non-resectable malignant gastric outlet obstruction (GOO). Studies of covered versus uncovered SEMS have yielded inconsistent results as a result of heterogeneity in design and patient population. We carried out a meta-analysis to compare covered and uncovered gastroduodenal SEMS.
  
  
  METHODS
  Using MEDLINE, Embase, and the Cochrane database, we identified 1624 patients from 13 prospective and retrospective studies that evaluated covered and uncovered SEMS for malignant GOO and were published until October 2016. We pooled data on SEMS dysfunction, technical and clinical success, and adverse events using the fixed-effect or random-effects model.
  
  
  RESULTS
  Compared with uncovered SEMS, covered SEMS did not show any significant difference in stent dysfunction risk (risk ratio [RR], 1.02; 95% confidence interval [CI], 0.79-1.32). A subgroup analysis of five randomized trials suggested a trend toward a lower dysfunction risk in covered SEMS (RR, 0.63; 95% CI, 0.45-0.88). Covered SEMS were associated with a lower occlusion risk (RR, 0.44; 95% CI, 0.28-0.68), but with a higher migration risk (RR, 4.28; 95% CI, 2.89-6.34). Technical and clinical success rates were comparable between the groups. Overall adverse events tended to be more frequent in covered SEMS (RR, 1.75; 95% CI, 1.09-2.83).
  
  
  CONCLUSIONS
  Outcomes of covered and uncovered gastroduodenal SEMS were comparable, although the lower dysfunction rate of covered SEMS observed in the analysis of randomized trials needs further investigation. Antimigration mechanisms for covered SEMS and identification of patients who can achieve longer patency from uncovered SEMS would help improve the outcomes of gastroduodenal SEMS.
authors.affiliation: Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, Tokoyo, Japan.|Department of Medical Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, USA.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Hamada
authors.affiliation: Department of Gastroenterology, Japanese Red Cross Medical Center, Tokoyo, Japan.
authors.forename: Ryunosuke
authors.initials: R
authors.lastname: Hakuta
authors.affiliation: Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, Tokoyo, Japan.
authors.forename: Naminatsu
authors.initials: N
authors.lastname: Takahara
authors.affiliation: Department of Hepato-Biliary-Pancreatic Medicine, The Cancer Institute Hospital of Japanese Foundation for Cancer Research, Tokyo, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Sasaki
authors.affiliation: Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, Tokoyo, Japan.
authors.forename: Yousuke
authors.initials: Y
authors.lastname: Nakai
authors.affiliation: Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, Tokoyo, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Isayama
authors.affiliation: Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, Tokoyo, Japan.
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Koike
mesh_terms: D020099:Coated Materials, Biocompatible; D017219:Gastric Outlet Obstruction / Q000175:diagnosis / Q000209:etiology / Q000601:surgery; D005773:Gastroscopy; D006801:Humans; D010166:Palliative Care / Q000379:methods*; D011474:Prosthesis Design; D000069322:Self Expandable Metallic Stents; D013274:Stomach Neoplasms / Q000150:complications*
chemical_list: D020099:Coated Materials, Biocompatible
keywords: gastrointestinal endoscopy; pancreatic neoplasm; pyloric stenosis; self-expandable metallic stent; stomach neoplasm