Vagus nerve stimulation (VNS) therapy in patients with treatment resistant depression: A systematic review and meta-analysis.

Author: Bottomley JM1, LeReun C2, Diamantopoulos A3, Mitchell S4, Gaynes BN5
Affiliation: <sup>1</sup>Amygdala Limited, Letchworth Garden City SG6 2AA, UK. Electronic address: <sup>2</sup>Independent Statistician, Sainte-Anne, Guadeloupe, France. Electronic address: <sup>3</sup>Symmetron Limited, London, UK. Electronic address: <sup>4</sup>Mtech Access Limited, Bicester, Oxfordshire OX26 4PP, UK. Electronic address: <sup>5</sup>Department of Psychiatry, UNC School of Medicine, Chapel Hill, NC, USA. Electronic address:
Conference/Journal: Compr Psychiatry.
Date published: 2019 Dec 12
Other: Volume ID: 98 , Pages: 152156 , Special Notes: doi: 10.1016/j.comppsych.2019.152156. [Epub ahead of print] , Word Count: 263

BACKGROUND: Vagus nerve stimulation (VNS) therapy is approved for treatment-resistant depression (TRD). A recent 5-year comparative study prompted this review of its impact in this very severe population. Previous systematic literature reviews (SLR) cited concerns in terms of missing studies or patient duplication.

METHODS: This SLR addressed these criticisms, assessed all outcomes of longer-term adjunctive VNS in all studies, irrespective of TRD severity, comparing where feasible with treatment-as-usual (TAU). We searched for adult VNS+TAU studies (January 1, 2000 to June 24, 2019). Comparative and single-arm studies were eligible. All reported efficacy, safety and quality of life (QOL) outcomes were assessed. Where possible, meta-analysis was used to calculate overall pooled effect estimates across studies at several time points.

RESULTS: Of 22 identified studies, there were two randomized controlled (RCT), sixteen single-arm and four non-randomized comparative studies. Numerous depression-specific, safety and QOL measures were reported. Meta-analysis was possible for three efficacy [Montgomery-Asberg Depression Rating Scale, Clinician Global Impression-Improvement, Hamilton Rating Scale for Depression] and three safety [serious adverse events, study drop-outs and all-cause mortality] but no QOL measures. Data beyond 2 years was not poolable. Analyses demonstrated that antidepressant benefits improved to 24 months and safety issues were minimal. Heterogeneity was high and statistically significant.

CONCLUSIONS: Despite limitations in the evidence base, our comprehensive summary of VNS+TAU outcomes suggests that this treatment provides improving benefit and hope for this very hard-to-treat chronic population. More comparative TRD studies should describe safety and QOL.

Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.

KEYWORDS: Long-term outcomes; Meta-analysis; Systematic review; Treatment resistant depression; Vagus nerve stimulation (VNS) therapy

PMID: 31978785 DOI: 10.1016/j.comppsych.2019.152156