Vagal Block Rivals Surgical Weight Loss?Tuesday, January 13, 2009
Well, not quite! Yesterday EnteroMedics announced the first 18-month results of their VBLOC-RF2 Feasibility Study.
This treatment involves blockade of vagal activity via an implantable electronic system (Maestro System) that delivers high frequency, intermittent low energy electrical signals through laparoscopically implanted leads. Blockade of vagal signals has been shown to reduce hunger, increase satiety and possibly have neuro-endocrine effects on liver and pancreas.
The still ongoing feasibility study includes 38 implanted subjects and shows excess weight loss (EWL) of 37.6% in 9 patients at 18 months, 28.1% in 17 patients at 12 months and 17.9% in 35 patients at six months of therapy. In line with the weight loss, improvements were also noted in diabetes and hypertension. No deaths or unanticipated adverse device events have been reported.
While the results are promising, it is important not to get misled by the reporting of EWL (a rather dubious construct generally reserved for surgical weight loss studies that describes loss of “excess” weight rather than absolute weight loss). The EWL, when translated to percent initial weight loss is generally far more modest (probably around 8-12%) but still at the higher end of what has been achieved with medical obesity treatments. It does however fall short of what is generally seen with obesity surgery (around 20-30% loss of initial weight).
Nevertheless, given our rather limited range of treatments for obesity, the results are clearly reason for some optimism. A much larger (n=294) randomized, prospective, double-blind, placebo-controlled study (EMPOWER) is currently being conducted in the United States and Australia is expected to report in the second half of this year.