Vagus nerve stimulation for chronic major depressive disorder: 12-month outcomes in highly treatment-refractory patients

BackgroundThere are limited treatment options for patients with chronic, treatment-refractory major depression who do not respond to routinely-available treatments. Vagus Nerve Stimulation (VNS) may represent an alternative to ablative neurosurgery for a specific group of patients.Methods12-month response rates for 28 patients with chronic (≥2 years) major depression who had failed to respond to ≥4 adequate treatment trials in the D03 European open clinical trial of VNS were described along with response rates for 13 consecutive patients who underwent VNS within the neurosurgical treatment programme in Dundee.ResultsIn the D03 cohort (N=28), the response rate at 12 months (defined as a 50% reduction in symptom score) was 35.7%. In the Dundee VNS case series (N=13), the equivalent response rate was 30.8%.LimitationsThese data are from unblinded and open studies, and there is no control group. Other factors may have contributed to some of the improvement seen, although this is unlikely in very chronic populations. Outcomes are not reported beyond 12 months.ConclusionResponse rates at 12 months for patients with chronic and highly-refractory major depression are broadly consistent with previously published results in more heterogeneous and less refractory clinical trial populations. In highly treatment-resistant patients, the rate of response with VNS at 12 m is at least twice that anticipated with 'treatment-as-usual'.