The Food and Drug Administration may soon approve a medical device that would be the first new treatment option for severely depressed patients in a generation, despite the misgivings of many experts who say there is little evidence that it works.
The pacemaker-like device, called a vagus nerve stimulator, is surgically implanted in the upper chest, and its wires are threaded into the neck, where it stimulates a nerve leading to the brain. It has been approved since 1997 for the treatment of some epilepsy patients, and the drug agency has told the manufacturer that it is now "approvable" for severe depression that is resistant to other treatment.
But in the only rigorously controlled trial so far in depressed patients, the stimulator was no more effective than surgery in which it was implanted but not turned on.
While some patients show significantly improved moods after having the $15,000 device implanted, most do not, the study found. And once the device is implanted, it is hard to remove entirely; surgeons say the wire leads are usually left inside the neck.
Proponents say that many severely depressed patients do not respond to antidepressants or electroshock therapy and that those patients are desperate for any treatment to relieve their suffering.
"These people have no other options, so we need to consider anything that shows potential to help," said Dr. Harold A. Sackeim, chief of biological psychiatry at the New York State Psychiatric Institute, who consults for Cyberonics Inc., the Houston company that makes the stimulator.
But Dr. Michael Thase, a psychiatrist at the University of Pittsburgh who consults for the company, said there was "simply not a good enough basis in evidence" for approval. While the device is promising, Dr. Thase said, "the shaky state of the evidence means we have to be very cautious with this and prepare for the possibility that the hoped-for benefit isn't there."
The drug agency has given mixed signals about the stimulator. In August 2004, it told Cyberonics in a letter that the treatment was not approvable, saying more information was needed. But in February, after the company provided more data, the agency changed that position, informing the company that the stimulator could now be approved. The company's stock price has fluctuated as investors try to anticipate the agency's decision, which the company is hopeful will come by the end of the month.
The Senate Finance Committee recently began looking into the F.D.A.'s potential reversal, but Cyberonics officials say they have been assured by the agency that this will have no bearing on its final decision.
In a conference call with reporters and analysts on Thursday, Robert Cummins, the company's chief executive, said no other treatment had been deemed approvable by the drug agency for stubbornly depressed patients. Clearly, he said, "the status quo for millions of Americans, their families, psychiatrists and payers is neither safe nor effective."
Still, some patient advocates and other experts are now questioning how the device has come so close to approval with such limited evidence for its effectiveness.
"I've never seen anything quite like this," said Dr. Peter Lurie, deputy director of health research at Public Citizen, a nonprofit group that is a frequent critic of the F.D.A. and the drug and medical-device industries. "What we could be setting ourselves up for is an epidemic of implantation of a device with no proven effectiveness."
Experts who were involved in the approval process say they were moved by the desperate prognosis for severe depression and by powerful testimonials.
At a critical meeting of an F.D.A. panel last June, six patients with chronic severe depression said they felt much better that the stimulator had been implanted, as part of an investigational study. At that meeting, the panel voted 5 to 2 to recommend that the device be approved.
One patient, Charles Donovan III of St. Louis, said the stimulator had saved his life. "I went from being a complete mental-health vegetable to someone who had the energy and confidence to do this book," Mr. Donovan said in an interview.
