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

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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.

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Financial disclosure

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

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Authors and Affiliations

  1. University of Minnesota, Minneapolis, MN, USA

    Charles J. Billington & Sayeed Ikramuddin

  2. Mayo Clinic, Rochester, MN, USA

    Michael G. Sarr & James M. Swain

  3. Institute of Weight Control, Sydney, Australia

    Roy Brancatisano & Anthony Brancatisano

  4. Flinders University, Adelaide, SA, Australia

    James Toouli & Lilian Kow

  5. University of California Irvine, Irvine, CA, USA

    Ninh T. Nguyen

  6. Scottsdale Bariatric Center, Scottsdale, AZ, USA

    Robin Blackstone

  7. Virginia Commonwealth University, Richmond, VA, USA

    James W. Maher

  8. Tufts Medical Center, Boston, MA, USA

    Scott Shikora

  9. Washington University School of Medicine, St. Louis, MO, USA

    Dominic N. Reeds & J. Christopher Eagon

  10. Oregon Health and Science University, Portland, OR, USA

    Bruce M. Wolfe & Robert W. O’Rourke

  11. Scripps Clinic, Del Mar, CA, USA

    Ken Fujioka & Mark Takata

  12. Stanford University School of Medicine, Stanford, CA, USA

    John M. Morton

  13. Johns Hopkins University, Baltimore, MD, USA

    Michael Schweitzer

  14. Cleveland Clinic Foundation, Cleveland, OH, USA

    Bipan Chand

  15. Cleveland Clinic Foundation, Weston, FL, USA

    Raul Rosenthal

  16. Department of Surgery, Mayo Clinic, 200 First St SW (GU 10-10), Rochester, MN, 55905, USA

    Michael G. Sarr

Authors
  1. Michael G. Sarr
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  2. Charles J. Billington
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  4. Anthony Brancatisano
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  5. James Toouli
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  6. Lilian Kow
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  7. Ninh T. Nguyen
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  8. Robin Blackstone
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  9. James W. Maher
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  10. Scott Shikora
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  11. Dominic N. Reeds
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  12. J. Christopher Eagon
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  13. Bruce M. Wolfe
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  14. Robert W. O’Rourke
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  15. Ken Fujioka
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  16. Mark Takata
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  17. James M. Swain
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  18. John M. Morton
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  19. Sayeed Ikramuddin
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  20. Michael Schweitzer
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  21. Bipan Chand
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  22. Raul Rosenthal
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Consortia

The EMPOWER Study Group

Corresponding author

Correspondence to Michael G. Sarr.

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Sarr, M.G., Billington, C.J., Brancatisano, R. et al. The EMPOWER Study: Randomized, Prospective, Double-Blind, Multicenter Trial of Vagal Blockade to Induce Weight Loss in Morbid Obesity. OBES SURG 22, 1771–1782 (2012). https://doi.org/10.1007/s11695-012-0751-8

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  • DOI: https://doi.org/10.1007/s11695-012-0751-8

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