A new study by Washington University School of Medicine in St. Louis researchers indicates that vagus nerve stimulation (VNS) delivered by a small implanted device provides lasting relief for individuals with severe treatment-resistant depression. The multicenter RECOVER clinical trial observed that a significant percentage of patients experienced sustained improvements in symptoms, quality of life, and daily function over two years, with some achieving remission. These findings aim to provide data for the U.S. Centers for Medicare and Medicaid Services (CMS) regarding future coverage of the therapy.
Study Overview and Methodology
The RECOVER trial evaluated the VNS Therapy System, manufactured and sponsored by LivaNova USA, Inc. The device is implanted under the skin in the chest and delivers electrical pulses to the left vagus nerve, which serves as a pathway between the brain and internal organs. The trial enrolled nearly 500 patients from 84 U.S. sites.
Participants in the study represented a population with severely treatment-resistant depression. On average, each patient had experienced depression for 29 years and had attempted 13 different treatments without success, including electroconvulsive therapy and transcranial magnetic stimulation. Three-quarters of the participants were unable to work due to their illness. For study control purposes, half of the implanted devices were initially inactive during the first year of the trial.
Key Findings
The study measured benefits through improvements in depressive symptoms, quality of life, and daily function. A "meaningful response" was defined as at least a 30% reduction in symptoms, while a "substantial response" indicated a 50% or greater symptom reduction.
- Sustained Benefits: Of 214 patients who received active VNS treatment from the trial's start, approximately 69% showed a meaningful response at 12 months. Among those who experienced a meaningful benefit at 12 months, over 80% maintained or increased these benefits at 24 months.
- Substantial Response: For patients achieving a substantial response at one year, 92% continued to experience benefits at the two-year mark.
- Delayed Improvement: Nearly one-third of participants who had not responded after one year of treatment reported benefits by the end of the second year, suggesting that the treatment may require an extended period to show effects for some individuals.
- Remission Rates: Over 20% of treated participants (39 individuals) achieved remission after 24 months, indicating their symptoms had improved to a level allowing normal daily functioning.
- Relapse Rates: Relapse rates among responders were consistently low throughout the study period.
Researcher Commentary
Lead author Charles Conway, MD, a professor of psychiatry at Washington University School of Medicine, stated that the trial's patient sample included some of the most severely ill individuals with treatment-resistant depression ever studied. He highlighted the observed sustained benefits and remission rates as significant for a condition typically associated with poor long-term outcomes, noting that the sustainability of benefit was atypical for this complex illness.
The findings were published on January 13 in the International Journal of Neuropsychopharmacology.