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Vagal nerve block therapy

Vagal nerve block therapy fails primary outcomes

12 months, 52 percent of participants in the vagal nerve block group achieved at least 20 percent; and 38 percent, at least 25 percent of excess weight loss

The use of vagal nerve block therapy compared with a sham control device did not meet either of the pre-specified co-primary efficacy objectives, according to a study published in JAMA. Nevertheless, weight loss in the vagal block group was statistically greater than in the sham device group.

In the study, Dr Sayeed Ikramuddinm from the University of Minnesota, Minneapolis, and colleagues randomly assigned 239 participants who had a 40-45 or 35-40 and one or more obesity-related condition to receive an implanted active vagal nerve block device (n=162) or an implanted sham (inactive) device (n=77). All participants received weight management education. The study was conducted at ten sites in the US and Australia between May and December 2011.

At 12 months in the intent-to-treat population, the average percentages of excess weight loss was 24.4 percent (9.2 percent of their initial body weight loss) in the vagal nerve block group and 15.9 percent (6.0 percent initial body weight loss) in the sham group, with an average difference of 8.5 percentage points, which did not meet the primary efficacy objective of achieving superiority with a 10 percentage-point margin. Weight loss was statistically greater in the vagal nerve block group.

At 12 months, 52 percent of participants in the vagal nerve block group achieved at least 20 percent; and 38 percent, at least 25 percent of excess weight loss, which did not meet the primary efficacy objective performance goals of at least 55 percent of participants achieving a 20 percent excess weight loss and 45 percent achieving a 25 percent excess weight loss.

The device, procedure, or therapy-related serious adverse event rate in the vagal nerve block group was 3.7 percent, significantly lower than the 15 percent primary safety objective goal. The adverse events more frequent in the vagal nerve block group were heartburn, indigestion and abdominal pain attributed to therapy; all were reported as mild or moderate in severity.

In an accompanying editorial, Drs David E Arterburn from the Group Health Research Institute, Seattle and David P Fisher from the Permanente Medical Group, Richmond, CA, write that  vagal nerve blockade plus moderately intensive lifestyle counselling does not appear to be much more effective than an intensive lifestyle programme.

They also note that based on comparisons with other studies, procedures for adjustable gastric banding, which reported a 50 percent excess weight loss; Roux-en-Y gastric bypass, a 68 percent excess weight loss; and vertical sleeve gastrectomy, a 65 percent excess weight loss, are clearly more effective for initial weight loss than vagal nerve blockade.

They also state that the rate of serious adverse events with vagal nerve blockade (8.6 percent) is clinically important.

They conclude that the study “does not include a discussion of how vagal nerve blockade compares with other obesity treatments in terms of costs. Although vagal nerve blockade therapy is an innovative approach, it does not appear to be a sustained, effective treatment for severe obesity."

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