Effectiveness and Safety of Vagus Nerve Stimulation for Severe Treatment-Resistant Major Depression in Clinical Practice After FDA Approval: Outcomes at 1 Year

Objective: To describe the outcomes of a consecutive series of depressed patients treated with vagus nerve stimulation (VNS) following US Food and Drug Administration (FDA) approval of this intervention. Method: We implanted a VNS device in 15 consecutive outpatients with treatment-resistant major depressive episodes, including 10 with major depressive disorder and 5 with bipolar disorder (DSM-IV criteria), between November 2005 and August 2006. Existing antidepressant treatment remained fixed as far as clinically possible. The primary outcome was change from baseline in the Beck Depression Inventory (BDI) score. Outcomes were assessed at 6 and 12 months postimplant and compared to those of the VNS pivotal efficacy trial that led to FDA approval of VNS. Results: The BDI score decreased significantly compared to baseline at 6 months (P < .05) and 12 months (P < .01), from a mean of 37.8 (SD = 7.8) before VNS activation to a mean of 24.6 (SD = 11.4) at 12 months. By 1 year, 28.6% (n=4) of the sample responded to VNS and 7.1% (n=1) remitted according to the BDI. Secondary outcomes on the Hamilton Depression Rating Scale 24-Item showed similar improvement at 1 year, with a 43% response rate (n=6) and 14.3% remission rate (n=2). No obvious predictors of response were detected. Side effects of VNS included hoarseness (73%), dyspnea (47%), nausea (40%), pain (33%), and anxiety (20%); no patient terminated treatment due to intolerable side effects. Conclusions: We found that a substantial minority of patients with extremely difficult-to-treat depressive disorders benefited from VNS in an ambulatory clinical practice, with outcomes comparable to those observed in previous VNS efficacy studies and with a similar side effect profile.