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., Competing Interests: Declaration of competing interest AJR has received consulting fees from Compass Inc., Curbstone Consultant LLC, Emmes Corp., Evecxia Therapeutics, Inc., Holmusk Technologies, Inc., ICON, PLC, Johnson & Johnson (Janssen), LivaNova, MindStreet, Inc., Neurocrine Biosciences Inc., and Otsuka-US; speaking fees from LivaNova and Johnson & Johnson (Janssen); and royalties from Wolters Kluwer Health, Guilford Press, and the University of Texas Southwestern Medical Center, Dallas, TX (for the Inventory of Depressive Symptoms and its derivatives). He is also named coinventor on 2 patents: US Patent No. 7,795,033: Methods to Predict the Outcome of Treatment With Antidepressant Medication, Inventors: McMahon FJ, Laje G, Manji H, Rush AJ, Paddock S, Wilson AS; and US Patent No. 7,906,283: Methods to Identify Patients at Risk of Developing Adverse Events During Treatment With Antidepressant Medication, Inventors: McMahon FJ, Laje G, Manji H, Rush AJ, Paddock S. CRC has received research support from the American Foundation for Suicide Prevention, Assurex Health, August Busch IV Foundation, Barnes-Jewish Hospital Foundation, LivaNova, National Institute of Mental Health, and the Taylor Family Institute for Innovative Psychiatric Research; consulted for LivaNova and Sage Therapeutics; and was a part-time employee at the John Cochran VA Medical Center in St Louis. STA is a consultant to Genomind, LivaNova, Janssen, Neuronetics, and Sage Therapeutics and has received research support from Compass Pathways and Neuronetics. DLD receives payment for clinical services for a former research patient from LivaNova, is a speaker for Janssen (esketamine nasal spray), and conducts forensic consultations, independent medical evaluations, and legal testimony for various firms. MSG has received research support from Abbott, LivaNova, Neurolief, and Magnus Medical. He consults for Abbott, Hospital Corp of America, Jacob Zabara Family Foundation, Neurolief, and Sooma. JZ receives research support from Boehringer-Ingelheim, Compass Pathways, Hoffman-LaRoche, Johnson & Johnson (Janssen), LivaNova, Otsuka, Neurocrine Bioscience, and Sage Therapeutics and received consulting fees from Alfasigma USA and Johnson & Johnson (Janssen). MTB and BO are former employees of and current consultants for LivaNova. JQ received clinical research support from LivaNova; has speaker bureau membership with Myriad Neuroscience and AbbVie; is a consultant for Eurofarma; is a stockholder at Instituto de Neurociencias; and receives copyrights from Artmed Editora, Artmed Panamericana, and Elsevier/Academic Press. RMA is one of the owners of a multisite interventional psychiatry and clinical trials company, Seattle Neuropsychiatric Treatment Center; receives research funding from LivaNova and Compass Pathways; and previously received research funding from Alto Neuroscience. PRP is a consultant for LivaNova, Janssen Pharmaceuticals, Motif Neurotech, and Abbott Neuromodulation. GA receives research support from AbbVie, Accera, Axsome, Axovant, Biogen, Eisai, Eli Lilly, Neurotrope, Genentech, Intra-Cellular, Janssen, Lundbeck, Neurim, Novartis, Otsuka, Roche, Sage, Suven, and TransTech and is on the speakers bureau of and is a consultant for AbbVie, Acadia, Alkermes, Axsome, Biogen, Janssen, Idorsia, Lundbeck, Myriad, Neurocrine, Nestle, Otsuka, Sage, Sunovion, Teva, and Takeda. HL has received consulting and/or speaking fees from Alkermes, Axsome, Intra-Cellular, Janssen, Karuna, Sage, Teva, and Vanda Pharmaceuticals; conducts forensic consultations, independent medical evaluations, and legal testimony for various firms; and co-owns Florida Center for TMS. ZN is a consultant to LivaNova, Magnus Medical, and Motif and has also received research support from LivaNova. LM has received research funding administered through Stony Brook University from Janssen Pharmaceuticals (developer of esketamine) to conduct clinical trials with esketamine, received research funding administered through Stony Brook University from LivaNova (developer of VNS technology) to conduct clinical trials with VNS, and served as a consultant and member of the Spravato Speaker Bureau for Janssen Pharmaceuticals. JIB receives research support from Teva Pharmaceutical Industries Ltd and from Relmada Therapeutics for clinical trials both administered through Southern Illinois UniversitySchool of Medicine. He has received research support from Janssen Research and Development to conduct clinical trials with esketamine also administered through the Southern Illinois UniversitySchool of Medicine. BJM received research support from NIH, NSF, Wellcome Leap, PCORI, Health Rhythms, LivaNova, Compass, and Abbott. JB is a partner and shareholder for the Neuroscience and TMS Treatment Center, as well as a co-owner of Cromwell Medical, a management service organization. He receives speaking fees for the Clinical TMS Society and is a paid clinical content reviewer for the Neuroscience Education Institute. YS has no conflict of interest to declare. CC has received research support for conducting clinical trials from AFSP, Clexio, ATAI, and Janssen and consulting fees from Compass Therapeutics and Boehringer. JWM has received consulting fees from Biohaven Pharmaceuticals, Inc., Clinilabs, Inc., Clexio Biosciences, Ltd., Compass Pathfinder, Plc., Janssen Pharmaceuticals, KetaMed, Inc., LivaNova, Merck & Co., Inc., Otsuka Pharmaceutical, Ltd., and Xenon Pharmaceuticals, Inc. KR has no conflict of interest to declare. PBR receives research support for conducting clinical trials from LivaNova Corporation and The George Institute. He has also participated in an advisory board for LivaNova Corporate. Y-CL is an employee of LivaNova. SM and JW are employees of LivaNova and hold stock options. HAS serves as a scientific advisor and receives consulting fees from Cerebral Therapeutics, Holmusk Technologies, LivaNova, MECTA Corporation, Neurolief, Neuronetics, Parow Entheobiosciences, and SigmaStim; receives honoraria and royalties from Elsevier and Oxford University Press; is the inventor of nonremunerative US patents for Focal Electrically Administered Seizure Therapy (FEAST), titration in the current domain in ECT, and the adjustment of current in ECT devices, each held by the SigmaStim Corporation; and is also the originator of magnetic seizure therapy (MST)., (Copyright © 2024. Published by Elsevier Inc.)