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Med Devices (Auckl). 2013;6:17-35. doi: 10.2147/MDER.S41017. Epub 2013 Mar 1.

A patient-level meta-analysis of studies evaluating vagus nerve stimulation therapy for treatment-resistant depression.

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1
Berry Consultants, Austin, TX, USA.

Abstract

OBJECTIVE:

To compare response and remission rates in depressed patients with chronic treatment-resistant depression (TRD) treated with vagus nerve stimulation (VNS) Therapy(®) plus treatment as usual (VNS + TAU) or TAU alone in a meta-analysis using Bayesian hierarchical models.

DATA SOURCES AND STUDY SELECTION:

Six outpatient, multicenter, clinical trials that have evaluated VNS + TAU or TAU in TRD, including two single-arm studies of VNS + TAU (n = 60 and n = 74), a randomized study of VNS + TAU versus TAU (n = 235), a randomized study of VNS + TAU comparing different VNS stimulation intensities (n = 331), a nonrandomized registry of VNS + TAU versus TAU (n = 636), and a single-arm study of TAU (n = 124) to provide longer-term, control data for comparison with VNS-treated patients.

DATA EXTRACTION:

A systematic review of individual patient-level data based on the intent-to-treat principle, including all patients who contributed more than one post-baseline visit. Response was based on the Montgomery-Åsberg Depression Rating Scale (MADRS) and the Clinical Global Impressions scale's Improvement subscale (CGI-I), as these were the two clinician-rated measures common across all or most studies. Remission was based on the MADRS.

RESULTS:

Outcomes were compared from baseline up to 96 weeks of treatment with VNS + TAU (n = 1035) versus TAU (n = 425). The MADRS response rate for VNS + TAU at 12, 24, 48, and 96 weeks were 12%, 18%, 28%, and 32% versus 4%, 7%, 12%, and 14% for TAU. The MADRS remission rate for VNS + TAU at 12, 24, 48, and 96 weeks were 3%, 5%, 10%, and 14% versus 1%, 1%, 2%, and 4%, for TAU. Adjunctive VNS Therapy was associated with a greater likelihood of response (odds ratio [OR] = 3.19, 95% confidence interval [CI]: 2.12, 4.66) and remission (OR = 4.99, CI: 2.93, 7.76), compared with TAU. For patients who had responded to VNS + TAU at 24 weeks, sustained response was more likely at 48 weeks (OR = 1.98, CI: 1.34, 3.01) and at 96 weeks (OR = 3.42, CI: 1.78, 7.31). Similar results were observed for CGI-I response.

CONCLUSION:

For patients with chronic TRD, VNS + TAU has greater response and remission rates that are more likely to persist than TAU.

KEYWORDS:

Bayesian meta-analysis; VNS Therapy; remission rate; response rate; treatment-resistant depression; vagus nerve stimulation

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