Vagus nerve stimulation in treatment-resistant depression: A one-year, randomized, sham-controlled trial

Few treatments are available for individuals with marked treatment-resistant depression (TRD).

Evaluate the safety and effectiveness of FDA-approved adjunctive vagus nerve stimulation (VNS) in patients with marked TRD.

This 12-month, multicenter, double-blind, sham-controlled trial included 493 adults with marked treatment-resistant major depression who were randomized to active or no-stimulation sham VNS for 12 months. The primary outcome was percent time in response across months 3-12, with response defined as a ≥50 % change from baseline on the Montgomery-Åsberg Depression Rating Scale (MADRS). Several secondary endpoints were evaluated.

Overall, 88.4 % of participants completed the trial. Percent time in MADRS response did not distinguish active from sham VNS. However, ratings from on-site clinicians (Clinical Global Inventory-Impression [CGI-I]), patients (Quick Inventory of Depressive Symptomology-Self Report [QIDS-SR]), and offsite masked raters (Quick Inventory of Depressive Symptomology-Clinician [QIDS-C]) revealed antidepressant benefits significantly favoring active VNS. Active VNS demonstrated significantly more percent time in response on the CGI-I (P = 0.004) and QIDS-SR (P = 0.049), and significantly more percent time in partial response (PR; symptom improvement ≥30 %) on the CGI-I (P < 0.001) and QIDS-C (P = 0.006) versus sham VNS. Active VNS exceeded sham VNS in rate of dyspnea (P = 0.035), a known side effect of VNS. No new adverse events were identified.

Percent time in MADRS response did not distinguish the treatment groups, but on multiple instruments time in response and PR showed a positive treatment effect. VNS was found safe and effective in participants with marked TRD.