Nerve Blocking Procedure Fails to Impress in Weight Loss Study
TUESDAY, Sept. 2, 2014 -- A device intended to help with weight loss by blocking a certain nerve linked to appetite and metabolism failed to meet expectations in a trial among obese patients.
Using electric impulses to block the vagus nerve, which runs between the brain and stomach, researchers hoped to suppress feelings of hunger. And, they did, just not to the extent they anticipated.
"A device that safely blocks the nerve that connects the brain to the gut can help people lose weight," said lead researcher Dr. Charles Billington, an endocrinologist and weight management specialist at the University of Minnesota in Minneapolis.
Just not as much as had been hoped.
The device, which is similar in size to a pacemaker, is implanted in the patient's abdomen with its electrodes touching the vagus nerve at a point between the esophagus and the stomach. Periodically, the device delivers electric impulses that block nerve impulses leaving patients with less of an appetite and feeling fuller, the researchers say.
After a year, Billington's team had hoped to see the 162 patients with the device lose 10 percent more excess weight than the 77 patients given a sham device.
However, the margin of weight loss was only 8.5 percent in favor of the device compared to the sham procedure. Patients with the real device lost about 24 percent of their excess weight, compared with 16 percent among those with the sham device, the researchers found.
Moreover, fewer people using the device lost significant amounts of weight (20 or 25 percent of their excess weight) than the researchers expected.
The report was published Sept. 3 in the Journal of the American Medical Association.
Dr. Philip Schauer, a bariatric surgeon, and director of the Bariatric and Metabolic Institute, Cleveland Clinic, said that given the modest amount of weight loss with the device compared with diet and exercise alone, he "wouldn't jump on the bandwagon yet."
"On the one hand the study does validate this concept, but on the other hand the amount of weight loss was modest," he said.
The difference in overall body weight lost was 3 percent between the device group and the sham device group, according to the study. Schauer questions whether that's enough of a difference to recommend the device over diet and exercise.
"For this device to be competitive it has to come between the weight loss we are getting with surgery and drug therapy," he said.
Weight loss is generally 8 to 10 percent of body weight with currently available drugs for weight loss, Schauer said. Weight loss with surgery is in the range of 25 to 30 percent, he said.
"So with a device like this, which is lower risk than surgery but greater risk than taking a pill, it needs to achieve an additional 15 to 20 percent weight loss," Schauer said. "It falls below expectations."
On a positive note, fewer patients had serious side effects related to the therapy than the researchers expected -- about 4 percent rather than the anticipated 15 percent, according to the study. Common side effects attributed to therapy were heartburn, indigestion and abdominal pain.
The device is being considered for approval by the U.S. Food and Drug Administration, Billington noted.
"If it is approved, it would be the first device for obesity treatment approved in 10 years and could provide an additional treatment option beyond the currently available medication and surgery," he said.
In another study in the same journal issue, an analysis of all the weight loss surgeries done in Michigan found that sleeve gastrectomy has become more common than Roux-en-Y gastric bypass surgery.
Both Roux-en-Y gastric bypass surgery and sleeve gastrectomy are types of weight loss -- or bariatric -- surgeries that make the stomach smaller. In a sleeve gastrectomy, a large part of the patient's stomach is removed. In a Roux-en-Y gastric bypass, a part of the stomach is used to create a pouch -- essentially a new smaller stomach.
Although long-term outcomes of sleeve gastrectomy are still unclear, it might be more popular because it seems to have a favorable safety profile. And, weight loss may continue for at least two to three years after the surgery, the researchers said.
Schauer said that sleeve gastrectomy may be increasing in popularity because many patients and doctors prefer it.
"Patients seem to want a less invasive option. Also, more surgeons are trained to do sleeve gastrectomy than Roux-en-Y gastric bypass surgery because it is an easier procedure to perform," he said.
For more about obesity, visit the U.S. National Library of Medicine.
Posted: September 2014