Group Attacks Depression Device Approval
Evidence Lacking Showing VNS Is Effective, Says Watchdog
WebMD News Archive
July 18, 2005 -- An FDA watchdog group criticized the agency's recent
approval of a new electrical stimulation device for depression Monday. It says
that the device has not been proven to work and may increase patients' risk of
The device, called a Vagus Nerve Stimulator (VNS), was approved for U.S.
sales Friday. But Public Citizen, an FDA and medical industry monitoring group,
says that the device does not meet government standards for safety and efficacy
and has not been adequately studied.
The device is also the subject of an ongoing investigation on Capitol Hill,
where some lawmakers are questioning its approval.
VNS is a small electrical generator that is surgically implanted under the
skin, where it delivers an electrical pulse every five seconds through wires
wrapped around the vagus nerve. The vagus nerve runs from the neck to the
brain. The nerve is thought to have some control over mood regulation.
John O'Reardon, MD, a psychiatrist and a paid consultant for the
manufacturer, called the approval "a reasonable scientific decision."
Severely depressed patients run a long-term risk of suicide attempts of nearly
20%, meaning they are already in danger without treatment, says O'Reardon,
chief of the treatment-resistant depression clinic at the University of
"It won't help every patient. If it helps 30% of my severely ill
patients that makes them a lot better off then they were previously,"
Device Rejected Last Year
FDA expert advisers voted 5-2 last year to recommend approval of the device
for treatment-resistant depression despite a study showing it failed to help
severely depressed patients after three months. In another study, 30% to 40%
who used VNS for one to two years had some improvement in their depression,
according to manufacturer Cyberonics Inc.
Several experts at the time expressed concern over data suggesting that some
patients who use VNS could be at increased risk for worsening depression or
Thirty-one of 235 participants in one study had bouts of deepening
depression, many reporting more than one episode. Twenty-five patients using
VNS also attempted suicide in several company studies.
The FDA rejected the device in August 2004, a decision that was appealed by
the manufacturer. The agency defended the reversal, noting that the surgically
implanted device was approved as a last resort for