Fran Lowry

June 23, 2014

HOLLYWOOD, Florida — Long-term use of vagal nerve stimulation (VNS) as an adjunctive therapy is safe and effective in patients with treatment-resistant depression (TRD), new research suggests.

Results of a 5-year observational study show that add-on VNS was safe and resulted in significantly better response and remission rates than usual treatment with no VNS in patients with TRD.

"We have 5 years of data for people with treatment-resistant depression implanted with VNS compared with a comparable population who do not have VNS, and these data show a 20- to 30-point separation both in response rates and remission rates on the Montgomery-Åsberg Depression Rating Scale [MADRS]," Scott Aaronson, MD, director of clinical research at Sheppard Pratt Health System, Baltimore, Maryland, told Medscape Medical News.

"As I was analyzing the data for the company, I was just getting blown away by the amount of separation that we are seeing. It's very rare in psychiatry to see 5-year data about anything, so this is very unusual, and the results are very positive," Dr. Aaronson said.

The findings were presented here at the American Society for Clinical Psychopharmacology (ASCP) 2014 Annual Meeting.

Insurers Won't Cover

An implantable device that is used for treatment-resistant epilepsy, VNS is also approved by the US Food and Drug Administration for treatment-resistant depression.

Dr. Scott Aaronson

However, medical insurers do not pay for VNS, and this has limited its use, Dr. Aaronson said.

"Insurers have not been very receptive to covering it, but we are hopeful that these kinds of data will convince them that this is a very valuable addition and that it should be a covered service," he said.

Dr. Aaronson and his team analyzed data obtained from 61 US centers that enrolled adults with chronic depression of at least 2 years' duration or who had recurrent depression that included at least 3 or more major depressive episodes. The study period was from 2006 to 2010.

All patients had to have experienced 4 or more adequate but not successful antidepressant treatments and then opted either to be implanted with VNS (n = 494 patients) or to receive treatment as usual (TAU, n = 301 patients) at the time of enrollment.

The average age of the patients at study entry was 49 years, the age at initial diagnosis of depression was 29 years, and the average number of failed treatments was 8, Dr. Aaronson said.

Patients in the VNS arm were more likely to experience remission than patients in the treatment-as-usual arm during the 5-year period, as shown on the MADRS scale (43.1% for VNS vs 22.8% for treatment as usual; P < .0001).

Remission also lasted longer for the VNS group than the treatment-as-usual group, as determined on the basis of MADRS scores (40 months for VNS vs 19 months for treatment as usual; P < 0.0065).

Patients in the VNS arm showed a greater response than patients in the treatment-as-usual arm during the 5-year study period with regard to the CGI-I scale as well (75.7% for VNS vs 47.1% for treatment as usual; P < .0001).

Similarly, VNS patients had a consistently better quality of life as rated by the Quality of Life, Enjoyment and Satisfaction Questionnaire than did patients receiving treatment as usual (P < .0001).

Encouraging Results

"The results of this study are encouraging," Philip Gerretsen, MD, from the Center for Addiction and Mental Health and the University of Toronto, Canada, told Medscape Medical News.

"However, the findings require replication with a randomized controlled trial to include a sham condition, as there is a high likelihood of a placebo effect both in this population and with an invasive procedure such as VNS," Dr. Gerretsen, who was not part of the study, said.

The study was sponsored by Cyberonics, Inc. Dr. Aaronson reported financial relationships with Sheppard Pratt, Genomind, Sunovion, and Takeda/Lundbeck. Dr. Gerretson reported no relevant financial relationships.

American Society of Clinical Psychopharmacology (ASCP) 2014 Annual Meeting. Abstract 34. Presented June 16, 2014.


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