title: Comparison of partially covered nitinol stents with partially covered stainless stents as a historical control in a multicenter study of distal malignant biliary obstruction: the WATCH study.
abstract: BACKGROUND
  Covered self-expandable metal stents (CSEMSs) were developed to prevent tumor ingrowth, but stent migration is one of the problems with CSEMSs.
  
  
  OBJECTIVE
  To evaluate a new, commercially available CSEMS with flared ends and low axial force compared with a commercially available CSEMS without the anti-migration system and high axial force.
  
  
  METHODS
  Multicenter, prospective study with a historical cohort.
  
  
  METHODS
  Twenty Japanese referral centers.
  
  
  METHODS
  This study involved patients with unresectable distal malignant biliary obstruction.
  
  
  METHODS
  Placement of a new, commercially available, partially covered SEMS.
  
  
  METHODS
  Recurrent biliary obstruction rate, time to recurrent biliary obstruction, stent-related complications, survival.
  
  
  RESULTS
  Between April 2009 and March 2010, 141 patients underwent partially covered nitinol stent placement, and between May 2001 and January 2007, 138 patients underwent placement of partially covered stainless stents as a historical control. The silicone cover of the partially covered nitinol stents prevented tumor ingrowth. There were no significant differences in survival (229 vs 219 days; P = .250) or the rate of recurrent biliary obstruction (33% vs 38%; P = .385) between partially covered nitinol stents and partially covered stainless stents. Stent migration was less frequent (8% vs 17%; P = .019), and time to recurrent biliary obstruction was significantly longer (373 vs 285 days; P = .007) with partially covered nitinol stents. Stent removal was successful in 26 of 27 patients (96%).
  
  
  CONCLUSIONS
  Nonrandomized, controlled trial.
  
  
  CONCLUSIONS
  Partially covered nitinol stents with an anti-migration system and less axial force demonstrated longer time to recurrent biliary obstruction with no tumor ingrowth and less stent migration.
authors.affiliation: Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Isayama
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Mukai
authors.forename: Takao
authors.initials: T
authors.lastname: Itoi
authors.forename: Iruru
authors.initials: I
authors.lastname: Maetani
authors.forename: Yousuke
authors.initials: Y
authors.lastname: Nakai
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kawakami
authors.forename: Ichiro
authors.initials: I
authors.lastname: Yasuda
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Maguchi
authors.forename: Shomei
authors.initials: S
authors.lastname: Ryozawa
authors.forename: Keiji
authors.initials: K
authors.lastname: Hanada
authors.forename: Osamu
authors.initials: O
authors.lastname: Hasebe
authors.forename: Kei
authors.initials: K
authors.lastname: Ito
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Kawamoto
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Mochizuki
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Igarashi
authors.forename: Atsushi
authors.initials: A
authors.lastname: Irisawa
authors.forename: Tamito
authors.initials: T
authors.lastname: Sasaki
authors.forename: Osamu
authors.initials: O
authors.lastname: Togawa
authors.forename: Taro
authors.initials: T
authors.lastname: Hara
authors.forename: Hideki
authors.initials: H
authors.lastname: Kamada
authors.forename: Nobuo
authors.initials: N
authors.lastname: Toda
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Kogure
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000497:Alloys; D001650:Bile Duct Neoplasms / Q000150:complications / Q000473:pathology; D002779:Cholestasis / Q000209:etiology / Q000628:therapy*; D020878:Device Removal; D005260:Female; D005706:Gallbladder Neoplasms / Q000150:complications / Q000473:pathology; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D010190:Pancreatic Neoplasms / Q000150:complications / Q000473:pathology; D016016:Proportional Hazards Models; D011474:Prosthesis Design; D011475:Prosthesis Failure; D012008:Recurrence; D012828:Silicones; D013193:Stainless Steel; D015607:Stents / Q000009:adverse effects; D013997:Time Factors
chemical_list: D000497:Alloys; D012828:Silicones; D013193:Stainless Steel; C013616:nitinol