title: Durability of the balloon-expandable covered versus bare-metal stents in the Covered versus Balloon Expandable Stent Trial (COBEST) for the treatment of aortoiliac occlusive disease.
abstract: OBJECTIVE
  The Covered vs Balloon Expandable Stent Trial (COBEST) is the first multicenter trial to investigate the patency of covered stents (CSs) and bare-metal stents (BMSs) in the treatment of aortoiliac arterial disease. The short-term results demonstrated that CSs were superior to BMSs in maintaining patency for TransAtlantic Inter-Society Consensus (TASC) C and D lesions at 18 months and were equivalent to BMSs for TASC B lesions. The current study was conducted to determine if the initial patency advantage of CSs over BMSs was sustained at the 5-year follow-up.
  
  
  METHODS
  A retrospective post hoc analysis of COBEST was performed. Originally, 125 patients with 168 iliac arteries were prospectively enrolled and randomly assigned to receive a CS or BMS. In this study, 77 of the 125 patients (61.6%; 119 limbs) were assessed at 60 months for the primary and secondary end points, with particular attention paid to the outcomes stratified according to TASC lesion severity. The primary end point was the rate of binary stenosis or freedom from stent occlusion of the treated area, as determined by ultrasound imaging or quantitative visual angiography.
  
  
  RESULTS
  The 5-year results of the COBEST showed that the CS had a significantly higher patency rate than the BMS at 18, 24, 48, and 60 months (95.1%, 82.1%, 79.9%, 74.7% for CS vs 73.9%, 70.9%, 63% and 62.5% for BMS; log-rank test, P = .01). On multivariate analysis, the type of stent used (hazard ratio [HR], 2.797; 95% confidence interval [CI], 1.471-5.318; P = .002) and the Rutherford classification (HR, 2.019; 95% CI, 1.278-3.191; P = .026) significantly affected the adjusted primary patency. On subgroup analysis, the CS showed significantly higher patency and a survival benefit compared with the BMS in TASC C and D lesions (HR, 8.639; 95% CI, 54.253-75.753; P = .003). Moreover, fewer patients received target limb revascularization in the CS group than in the BMS group (odds ratio, 2.32; 95% CI, 1.47-3.36; P = .02); however, there was no statistically significant difference in the rate of amputations between the groups.
  
  
  CONCLUSIONS
  The 5-year results of the COBEST demonstrated that the CS has an enduring patency advantage over the BMS in both the short and long terms. Furthermore, the CS showed acceptable patency rates for the treatment of more severe TASC C and D lesions, and patients who received a CS required fewer revascularization procedures. However, the choice of stent did not affect the rate of major limb amputations.
authors.affiliation: Department of Vascular Surgery, Royal Perth Hospital, Perth, Australia; School of Surgery, Faculty of Medicine, Dentistry, and Health Sciences, University of Western Australia, Perth, Australia. Electronic address: bibombe@iinet.net.au.
authors.forename: Bibombe P
authors.initials: BP
authors.lastname: Mwipatayi
authors.affiliation: Department of Vascular Surgery, Royal Perth Hospital, Perth, Australia.
authors.forename: Surabhi
authors.initials: S
authors.lastname: Sharma
authors.affiliation: Department of Vascular Surgery, Royal Perth Hospital, Perth, Australia.
authors.forename: Ali
authors.initials: A
authors.lastname: Daneshmand
authors.affiliation: University of New South Wales, Sydney, Australia; Prince of Wales Hospital, Sydney, Australia.
authors.forename: Shannon D
authors.initials: SD
authors.lastname: Thomas
authors.affiliation: Department of Vascular Surgery, Alexandra Hospital, Singapore.
authors.forename: Vikram
authors.initials: V
authors.lastname: Vijayan
authors.affiliation: Department of Vascular Surgery, Royal Perth Hospital, Perth, Australia.
authors.forename: Nishath
authors.initials: N
authors.lastname: Altaf
authors.affiliation: Department of Vascular Surgery, Sir Charles Gairdner Hospital, Perth, Australia.
authors.forename: Marek
authors.initials: M
authors.lastname: Garbowski
authors.affiliation: Department of Vascular Surgery, Gold Coast Hospital, Queensland, Australia.
authors.forename: Mark
authors.initials: M
authors.lastname: Jackson
mesh_terms: D000368:Aged; D000671:Amputation, Surgical; D000800:Angioplasty, Balloon / Q000009:adverse effects / Q000295:instrumentation* / Q000401:mortality; D001018:Aortic Diseases / Q000000981:diagnostic imaging / Q000401:mortality / Q000503:physiopathology / Q000628:therapy*; D001157:Arterial Occlusive Diseases / Q000000981:diagnostic imaging / Q000401:mortality / Q000503:physiopathology / Q000628:therapy*; D005260:Female; D006801:Humans; D007083:Iliac Artery / Q000000981:diagnostic imaging / Q000503:physiopathology; D053208:Kaplan-Meier Estimate; D023821:Limb Salvage; D016015:Logistic Models; D008297:Male; D008670:Metals; D008875:Middle Aged; D015999:Multivariate Analysis; D016017:Odds Ratio; D016016:Proportional Hazards Models; D011474:Prosthesis Design; D016032:Randomized Controlled Trials as Topic; D012008:Recurrence; D012189:Retrospective Studies; D012307:Risk Factors; D015607:Stents; D013997:Time Factors; D016896:Treatment Outcome; D014654:Vascular Patency
chemical_list: D008670:Metals