title: The EMPOWER study: randomized, prospective, double-blind, multicenter trial of vagal blockade to induce weight loss in morbid obesity.
abstract: BACKGROUND
  Intermittent, reversible intraabdominal vagal blockade (VBLOC® Therapy) demonstrated clinically important weight loss in feasibility trials. EMPOWER, a randomized, double-blind, prospective, controlled trial was conducted in USA and Australia.
  
  
  METHODS
  Five hundred three subjects were enrolled at 15 centers. After informed consent, 294 subjects were implanted with the vagal blocking system and randomized to the treated (n = 192) or control (n = 102) group. Main outcome measures were percent excess weight loss (percent EWL) at 12 months and serious adverse events. Subjects controlled duration of therapy using an external power source; therapy involved a programmed algorithm of electrical energy delivered to the subdiaphragmatic vagal nerves to inhibit afferent/efferent vagal transmission. Devices in both groups performed regular, low-energy safety checks. Data are mean ± SEM.
  
  
  RESULTS
  Study subjects consisted of 90 % females, body mass index of 41 ± 1 kg/m(2), and age of 46 ± 1 years. Device-related complications occurred in 3 % of subjects. There was no mortality. 12-month percent EWL was 17 ± 2 % for the treated and 16 ± 2 % for the control group. Weight loss was related linearly to hours of device use; treated and controls with ≥ 12 h/day use achieved 30 ± 4 and 22 ± 8 % EWL, respectively.
  
  
  CONCLUSIONS
  VBLOC® therapy to treat morbid obesity was safe, but weight loss was not greater in treated compared to controls; clinically important weight loss, however, was related to hours of device use. Post-study analysis suggested that the system electrical safety checks (low charge delivered via the system for electrical impedance, safety, and diagnostic checks) may have contributed to weight loss in the control group.
authors.affiliation: Mayo Clinic, Rochester, MN, USA. sarr.michael@mayo.edu
authors.forename: Michael G
authors.initials: MG
authors.lastname: Sarr
authors.forename: Charles J
authors.initials: CJ
authors.lastname: Billington
authors.forename: Roy
authors.initials: R
authors.lastname: Brancatisano
authors.forename: Anthony
authors.initials: A
authors.lastname: Brancatisano
authors.forename: James
authors.initials: J
authors.lastname: Toouli
authors.forename: Lilian
authors.initials: L
authors.lastname: Kow
authors.forename: Ninh T
authors.initials: NT
authors.lastname: Nguyen
authors.forename: Robin
authors.initials: R
authors.lastname: Blackstone
authors.forename: James W
authors.initials: JW
authors.lastname: Maher
authors.forename: Scott
authors.initials: S
authors.lastname: Shikora
authors.forename: Dominic N
authors.initials: DN
authors.lastname: Reeds
authors.forename: J Christopher
authors.initials: JC
authors.lastname: Eagon
authors.forename: Bruce M
authors.initials: BM
authors.lastname: Wolfe
authors.forename: Robert W
authors.initials: RW
authors.lastname: O'Rourke
authors.forename: Ken
authors.initials: K
authors.lastname: Fujioka
authors.forename: Mark
authors.initials: M
authors.lastname: Takata
authors.forename: James M
authors.initials: JM
authors.lastname: Swain
authors.forename: John M
authors.initials: JM
authors.lastname: Morton
authors.forename: Sayeed
authors.initials: S
authors.lastname: Ikramuddin
authors.forename: Michael
authors.initials: M
authors.lastname: Schweitzer
authors.forename: Bipan
authors.initials: B
authors.lastname: Chand
authors.forename: Raul
authors.initials: R
authors.lastname: Rosenthal
mesh_terms: D001066:Appetite; D001315:Australia / Q000453:epidemiology; D001340:Autonomic Nerve Block / Q000379:methods*; D015992:Body Mass Index; D004311:Double-Blind Method; D004599:Electric Stimulation Therapy / Q000295:instrumentation*; D004567:Electrodes, Implanted; D005260:Female; D006801:Humans; D006815:Hunger; D008297:Male; D008875:Middle Aged; D009767:Obesity, Morbid / Q000453:epidemiology / Q000503:physiopathology / Q000628:therapy*; D011446:Prospective Studies; D011795:Surveys and Questionnaires; D016896:Treatment Outcome; D014481:United States / Q000453:epidemiology; D014630:Vagus Nerve; D015431:Weight Loss