title: Comparative performance of uncoated, self-expanding metal biliary stents of different designs in 2 diameters: final results of an international multicenter, randomized, controlled trial.
abstract: BACKGROUND
  The Wallstent has remained the industry standard for biliary self-expanding metal stents (SEMSs). Recently, stents of differing designs, compositions, and diameters have been developed.
  
  
  OBJECTIVE
  To compare the new nitinol 6-mm and 10-mm Zilver stents with the 10-mm stainless steel Wallstent and determine the mechanism of obstruction.
  
  
  METHODS
  Randomized, prospective, controlled study.
  
  
  METHODS
  Nine centers experienced in SEMS placement during ERCP.
  
  
  METHODS
  A total of 241 patients presenting between September 2003 and December 2005 with unresectable malignant biliary strictures at least 2 cm distal to the bifurcation.
  
  
  METHODS
  Stent occlusions requiring reintervention and death.
  
  
  RESULTS
  At interim analysis, a significant increase in occlusions was noted in the 6-mm Zilver group at the P = .04 level, resulting in arm closure but continued follow-up. Final study arms were 64, 88, and 89 patients receiving a 6-mm Zilver, 10-mm Zilver, and 10-mm Wallstent, respectively. Stent occlusions occurred in 25 (39.1%) of the patients in the 6-mm Zilver arm, 21 (23.9%) of the patients in the 10-mm Zilver arm, and 19 (21.4%) of the patients in the 10-mm Wallstent arm (P = .02). The mean number of days of stent patency were 142.9, 185.8, and 186.7, respectively (P = .057). No differences were noted in secondary endpoints, and the study was ended at the 95% censored study endpoints. Biopsy specimens of ingrowth occlusive tissue revealed that 56% were caused by benign epithelial hyperplasia.
  
  
  CONCLUSIONS
  SEMS occlusions were much more frequent with a 6-mm diameter SEMS and equivalent in the two 10-mm arms despite major differences in stent design, material, and expansion, suggesting that diameter is the critical feature. Malignant tumor ingrowth produced only a minority of the documented occlusions.
authors.affiliation: Maine Medical Center, Portland, Maine, USA.
authors.forename: Burr J
authors.initials: BJ
authors.lastname: Loew
authors.forename: Douglas A
authors.initials: DA
authors.lastname: Howell
authors.forename: Michael K
authors.initials: MK
authors.lastname: Sanders
authors.forename: David J
authors.initials: DJ
authors.lastname: Desilets
authors.forename: Paul P
authors.initials: PP
authors.lastname: Kortan
authors.forename: Gary R
authors.initials: GR
authors.lastname: May
authors.forename: Raj J
authors.initials: RJ
authors.lastname: Shah
authors.forename: Yang K
authors.initials: YK
authors.lastname: Chen
authors.forename: Willis G
authors.initials: WG
authors.lastname: Parsons
authors.forename: Robert H
authors.initials: RH
authors.lastname: Hawes
authors.forename: Peter B
authors.initials: PB
authors.lastname: Cotton
authors.forename: Adam A
authors.initials: AA
authors.lastname: Slivka
authors.forename: Jawad
authors.initials: J
authors.lastname: Ahmad
authors.forename: Glen A
authors.initials: GA
authors.lastname: Lehman
authors.forename: Stuart
authors.initials: S
authors.lastname: Sherman
authors.forename: Horst
authors.initials: H
authors.lastname: Neuhaus
authors.forename: Brigitte M
authors.initials: BM
authors.lastname: Schumacher
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000497:Alloys; D001650:Bile Duct Neoplasms / Q000150:complications / Q000473:pathology; D002404:Catheterization / Q000379:methods*; D002760:Cholangiopancreatography, Endoscopic Retrograde / Q000379:methods; D002779:Cholestasis / Q000209:etiology / Q000401:mortality / Q000473:pathology* / Q000628:therapy*; D005260:Female; D006801:Humans; D007391:International Cooperation; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D010166:Palliative Care / Q000379:methods*; D018579:Patient Selection; D011336:Probability; D011379:Prognosis; D011446:Prospective Studies; D011474:Prosthesis Design; D011475:Prosthesis Failure; D011788:Quality of Life; D018570:Risk Assessment; D013193:Stainless Steel; D015607:Stents; D016019:Survival Analysis; D019452:Terminally Ill; D016896:Treatment Outcome
chemical_list: D000497:Alloys; D013193:Stainless Steel; C013616:nitinol