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

Characterizing the effects of vagus nerve stimulation on symptom improvement in markedly treatment-resistant major depressive disorder: A RECOVER trial report

BACKGROUND

The RECOVER trial randomized 493 patients with markedly treatment-resistant major depressive disorder to treatment-as-usual with or without active vagus nerve stimulation (VNS Therapy). While the primary outcome measure did not statistically separate the treatment conditions, the field may lack optimal metrics for quantifying symptom improvement in markedly treatment-resistant patients.

METHODS

This study examined the impact of three factors on sensitivity to clinical improvement across the total RECOVER sample and to differences in the effectiveness of the randomized conditions, systematically varying outcome classification (remission, response, and partial response), observation period (3-12 months, 6-12 months, 10-12 months and last observation), and depression rating scale.

RESULTS

Effect sizes for detecting therapeutic change across the total sample and the difference in effectiveness between the randomized groups were markedly higher for partial response than response or remission classifications. Longer observation periods produced larger therapeutic effects across the sample, but the effect sizes for the randomized treatment differences were substantially higher in the final 10-12 month period. The MADRS showed the least sensitivity to change across the sample and between the treatment groups. Using the partial response classification and the 10-12 month observation period, a significant difference between the groups was obtained for 3 of 4 depression scales.

LIMITATIONS

The findings derive from a retrospective assessment of alternative outcome metrics.

CONCLUSION

In a large randomized controlled trial of VNS for markedly treatment-resistant depression, the magnitude of therapeutic effects and separation of treatment groups differed as a function of outcome classification, measurement period, and rating scale.

Invasive Neurostimulation for the Treatment of Epilepsy

Although electricity has been used in medicine for thousands of years, bioelectronic medicine for treating epilepsy has become increasingly common in recent years. Invasive neurostimulation centers primarily around three approaches: vagus nerve stimulation (VNS), responsive neurostimulation (RNS), and deep brain stimulation (DBS). These approaches differ by target (e.g., cranial nerve, cortex, or thalamus) and stimulation parameters (e.g., triggered stimulation or continuous stimulation). Although typically noncurative, these approaches can dramatically reduce the seizure burden and offer patients new treatment options. There remains much to be understood about optimal targets and individualized stimulation protocols. Objective markers of seizure burden and biomarkers that quickly quantify neural excitability are still needed. In the future, bioelectronic medicine could become a curative approach that remodels neural networks to reduce pathological activity.

Effects of vagus nerve stimulation on daily function and quality of life in markedly treatment-resistant major depression: Findings from a one-year, randomized, sham-controlled trial

BACKGROUND

Depression treatments aim to minimize symptom burden and optimize quality of life (QoL) and psychosocial function.

OBJECTIVE

Compare the effects of adjunctive versus sham vagus nerve stimulation (VNS) on QoL and function in markedly treatment-resistant depression (TRD).

METHODS

In this multicenter, double-blind, sham-controlled trial, 493 adults with TRD and ≥4 adequate but unsuccessful antidepressant treatment trials (current episode) were randomized to active (n = 249) or sham (n = 244) VNS (plus treatment as usual) over a 12-month observation period. Quarterly outcomes included QoL with the Q-LES-Q, Mini-Q-LES-Q, and EQ-5D-5L, and function with the WHODAS 2.0 and Work Productivity and Activity Impairment Questionnaire (WPAI) item 6. Differences between treatment groups in change in scores from baseline and percentage of time with a meaningful response in Q-LES-Q, Mini-Q-LES-Q, and WPAI item 6 scores were analyzed.

RESULTS

Active VNS was superior to sham in mean change in scores from baseline in the Mini-Q-LES-Q (P = 0.050) and WPAI item 6 (health condition's effect on regular activities [P = 0.050]) used as continuous variables, with a similar trend for Q-LES-Q (P = 0.061). Active VNS was superior to sham in time spent in clinically meaningful benefit (categorical analyses) using the Q-LES-Q (P = 0.029), Mini-Q-LES-Q (P = 0.011), and WPAI item 6 (P = 0.039). The WHODAS 2.0 (P = 0.304) and EQ-5D visual analog scale (P = 0.125) failed to reveal between-group differences.

CONCLUSION

Active VNS was superior to sham VNS in improving QoL and psychosocial function in patients with TRD. VNS has a broader therapeutic impact than symptom improvement alone in patients with marked psychosocial impairment.