May 11, 2005
Electronic Device Should Not Be Approved for Treatment of Depression, Public Citizen Tells FDA
Effectiveness of VNS Therapy Unproved, Safety Questionable
WASHINGTON, D.C. – An electronic device implanted in the base of the neck that is currently used to treat epilepsy patients should not be approved for use in patients with treatment-resistant depression, Public Citizen told the U.S. Food and Drug Administration (FDA) today.
In a letter sent to Daniel Schultz, the director of the FDA’s Center for Devices and Radiologic Health, Public Citizen questioned both the effectiveness of the device and the soundness of the studies submitted by the company seeking approval.
The device, known as Vagus Nerve Stimulation (VNS) therapy, was developed by Cyberonics of Houston, Texas. It consists of a pulse generator that delivers electrical signals to the left cervical vagus nerve, a major nerve that connects to the heart, the gastrointestinal tract, the brain and other parts of the body. It is programmed to be on for 30 seconds and off for five minutes.
The device was approved for use in epilepsy patients in 1997 and is currently used by approximately 30,000 people. If the FDA approves the device for severely depressed patients, it would have access to a market of 4 million patients, according to the Cyberonics.
“The principle is simple: If it doesn’t work, it shouldn’t be approved,” said Dr. Peter Lurie, deputy director of Public Citizen’s Health Research Group. “The FDA would never approve a drug under these conditions. They certainly shouldn’t approve this device.”
The agency itself has raised questions about increased suicides, worsening depression and sudden death in patients using this device – all of which require further investigation, Public Citizen said.
In 2003, Cyberonics asked the FDA to approve the use of the device in patients 18 or older with chronic or recurrent depression who had failed to respond to two or more antidepressant treatments. In 2004, the FDA sent a “major deficiency letter” that cited serious flaws in the company’s data. The company responded, and an advisory committee later voted 5-2 to approve the device with conditions. The FDA took the unusual step of overruling the committee’s recommendation because of concerns about the device’s effectiveness as well as data showing worsening depression in many VNS patients.
The company submitted more data, and the FDA reversed itself in February 2005 and reportedly told the company that the device was approvable.
The company has submitted data about only a single randomized, controlled trial (in which all patients had the device implanted but only half had the device turned on), and that trial failed to convincingly demonstrate the effectiveness of the device. It also produced long-term, non-randomized data comparing VNS to another comparison group, but an FDA statistician called that analysis “highly questionable.”
“The FDA should not let justified empathy for this patient population lead to the unjustified approval of a device that does not come close to meeting the agency’s approval standards and may do more harm than good,” said Nicholas Stine, a researcher at Public Citizen who worked on the letter.
To read a copy of the letter, click here.