title: Features of malignant biliary obstruction affecting the patency of metallic stents: a multicenter study.
abstract: BACKGROUND
  Although placement of a metallic stent is an established therapeutic option for the palliation of patients with malignant biliary obstruction, it remains unclear which stricture-related or stent-related factors influence stent patency.
  
  
  METHODS
  Metallic stents were inserted endoscopically in 68 patients (38 men, 30 women; mean age 70.2 plus minus 8.5 years) with malignant biliary obstruction. Patency rates were prospectively analyzed according to malignant stricture characteristics, including length, morphologic type, and degree of narrowing. Furthermore, patient age, initial serum bilirubin level, length of stent, time to adequate expansion, and the location of the distal end of the stent were evaluated as possible factors affecting the stent patency. Stent patency was assessed by using the survival analysis of the Kaplan-Meier estimation and Cox regression analysis.
  
  
  RESULTS
  Median overall stent patency was 231 days (range 27-379 days) and the overall rate of stent occlusion 41.2% (28/68). The causes of occlusion were tumor ingrowth in 23 patients (33.8%), distal overgrowth in 3 (4.4%), proximal overgrowth in 1 (1.5%), and encrustation with sludge in 1 patient (1.5%). No significant differences in patency rates according to patient age, initial serum bilirubin level, primary tumor type, length and morphologic type of stricture, and length and location of the distal end of the stent were found. Cox regression analysis demonstrated that the degree of narrowing assessed by cannula or guidewire passage and the time to adequate expansion of the stent were independent factors associated with stent patency.
  
  
  CONCLUSIONS
  Early expansion of the stent and easy passage of larger-caliber instruments through the stricture were favorable factors for long-term patency of the Wallstent.
authors.affiliation: Department of Internal Medicine, Yonsei University Wonju College of Medicine, 162 Ilsan-Dong, Wonju, 220-701 Korea.
authors.forename: Hyun Soo
authors.initials: HS
authors.lastname: Kim
authors.forename: Dong Ki
authors.initials: DK
authors.lastname: Lee
authors.forename: Ho Gak
authors.initials: HG
authors.lastname: Kim
authors.forename: Jong Jae
authors.initials: JJ
authors.lastname: Park
authors.forename: Sang Heum
authors.initials: SH
authors.lastname: Park
authors.forename: Jin Hong
authors.initials: JH
authors.lastname: Kim
authors.forename: Byung Moo
authors.initials: BM
authors.lastname: Yoo
authors.forename: Im Hwan
authors.initials: IH
authors.lastname: Roe
authors.forename: Young Soo
authors.initials: YS
authors.lastname: Moon
authors.forename: Seung Jae
authors.initials: SJ
authors.lastname: Myung
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001649:Bile Duct Diseases / Q000209:etiology / Q000628:therapy*; D001650:Bile Duct Neoplasms / Q000150:complications; D001663:Bilirubin / Q000097:blood; D002760:Cholangiopancreatography, Endoscopic Retrograde; D003251:Constriction, Pathologic / Q000209:etiology / Q000628:therapy; D004867:Equipment Design; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008670:Metals; D008875:Middle Aged; D010166:Palliative Care; D010190:Pancreatic Neoplasms / Q000150:complications; D011446:Prospective Studies; D015607:Stents
chemical_list: D008670:Metals; D001663:Bilirubin