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Obesity Surgery

, Volume 22, Issue 11, pp 1771–1782 | Cite as

The EMPOWER Study: Randomized, Prospective, Double-Blind, Multicenter Trial of Vagal Blockade to Induce Weight Loss in Morbid Obesity

  • Michael G. SarrEmail author
  • Charles J. Billington
  • Roy Brancatisano
  • Anthony Brancatisano
  • James Toouli
  • Lilian Kow
  • Ninh T. Nguyen
  • Robin Blackstone
  • James W. Maher
  • Scott Shikora
  • Dominic N. Reeds
  • J. Christopher Eagon
  • Bruce M. Wolfe
  • Robert W. O’Rourke
  • Ken Fujioka
  • Mark Takata
  • James M. Swain
  • John M. Morton
  • Sayeed Ikramuddin
  • Michael Schweitzer
  • Bipan Chand
  • Raul Rosenthal
  • The EMPOWER Study Group
Clinical Research

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/m2, 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.

Keywords

Morbid obesity Vagal modulation Vagal blockade Neuromodulation Weight loss Satiety Blood pressure 

Notes

Financial disclosure

This study was funded entirely by EnteroMedics Inc, St. Paul, MN.

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Copyright information

© Springer Science + Business Media, LLC 2012

Authors and Affiliations

  • Michael G. Sarr
    • 2
    • 16
    Email author
  • Charles J. Billington
    • 1
  • Roy Brancatisano
    • 3
  • Anthony Brancatisano
    • 3
  • James Toouli
    • 4
  • Lilian Kow
    • 4
  • Ninh T. Nguyen
    • 5
  • Robin Blackstone
    • 6
  • James W. Maher
    • 7
  • Scott Shikora
    • 8
  • Dominic N. Reeds
    • 9
  • J. Christopher Eagon
    • 9
  • Bruce M. Wolfe
    • 10
  • Robert W. O’Rourke
    • 10
  • Ken Fujioka
    • 11
  • Mark Takata
    • 11
  • James M. Swain
    • 2
  • John M. Morton
    • 12
  • Sayeed Ikramuddin
    • 1
  • Michael Schweitzer
    • 13
  • Bipan Chand
    • 14
  • Raul Rosenthal
    • 15
  • The EMPOWER Study Group
  1. 1.University of MinnesotaMinneapolisUSA
  2. 2.Mayo ClinicRochesterUSA
  3. 3.Institute of Weight ControlSydneyAustralia
  4. 4.Flinders UniversityAdelaideAustralia
  5. 5.University of California IrvineIrvineUSA
  6. 6.Scottsdale Bariatric CenterScottsdaleUSA
  7. 7.Virginia Commonwealth UniversityRichmondUSA
  8. 8.Tufts Medical CenterBostonUSA
  9. 9.Washington University School of MedicineSt. LouisUSA
  10. 10.Oregon Health and Science UniversityPortlandUSA
  11. 11.Scripps ClinicDel MarUSA
  12. 12.Stanford University School of MedicineStanfordUSA
  13. 13.Johns Hopkins UniversityBaltimoreUSA
  14. 14.Cleveland Clinic FoundationClevelandUSA
  15. 15.Cleveland Clinic FoundationWestonUSA
  16. 16.Department of SurgeryMayo ClinicRochesterUSA

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