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J Clin Psychiatry 2023;84(3):22com14575

To cite: Weissman CR, Bermudes RA, Voigt J, et al. Repetitive transcranial magnetic stimulation for treatment-resistant depression: mismatch of evidence and insurance coverage policies in the United States. J Clin Psychiatry. 2023;84(3):22com14575.
To share: https://doi.org/10.4088/JCP.22com14575

© 2023 Physicians Postgraduate Press, Inc.

aDepartment of Psychiatry, University of California San Diego, La Jolla, California
bMindful Health Solutions, San Francisco, California
cMedical Device Consultants of Ridgewood, LLC, Ridgewood, New Jersey
dDepartment of Psychiatry, Brain and Mind Research Institute, Weill Cornell Medicine, New York, New York
eStanford Brain Stimulation Laboratory, Stanford University, Stanford, California
fTemerty Centre for Therapeutic Brain Intervention, Campbell Family Research Institute, Centre for Addiction and Mental Health and Department of Psychiatry, Temerty Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
gAustralian National University School of Medicine and Psychology, Canberra, Australia
*Corresponding author: Cory R. Weissman, MD, Department of Psychiatry, University of California San Diego, 9500 Gilman Dr, La Jolla, CA 92161 ([email protected]).

Major depressive disorder (MDD) is common and highly disabling. In the United States, the estimated 12-month prevalence of MDD is 8.9 million adults, of which one third (2.76 million) meet criteria for treatment-resistant depression (TRD).1 The most common definition of TRD is a minimum of 2 antidepressant medication failures of different classes at an adequate dosage and duration.2–4 Patients who develop TRD experience diminishing returns with each additional antidepressant medication trial, which highlights the need for alternative treatments at this critical point in the course of their depressive illness.3 There is significant burden associated with untreated TRD,5,6 as it is more disabling compared to MDD.7 This disease burden extends to medical comorbidities as well.8,9 The amount of time one is depressed, which is far lengthier in TRD, also predicts future disability.10 Patients with TRD experience large declines in quality of life and social functioning.11 Evidence also consistently shows the high lethality of TRD, with its strong association to suicidality.11,12 It is therefore imperative to make effective treatments available for patients diagnosed with TRD. While there is minimal evidence to guide treatment algorithms for patients with TRD, we do believe that current practices of prior authorization by insurance companies specifically overly restrict access to repetitive transcranial magnetic stimulation (rTMS), which is a treatment with proven effectiveness for TRD. In this commentary, we explore this case of overrestriction of access to rTMS in the United States through review of both the clinical evidence and the relevant economic policy.

Thanks to the diligent and innovative work of many researchers in the field, there are effective treatment options available for patients with TRD. The most effective and time-tested treatment for this patient population is electroconvulsive therapy (ECT). However, stigma, the risk of adverse cognitive effects, and side effect burden limit the acceptability of this treatment,13,14 leading to the use of ECT in less than 1% of patients with TRD.15 Intravenous (IV) ketamine and intranasal esketamine both demonstrate efficacy in TRD, although there is scant evidence for maintenance IV ketamine, and both treatments are limited by the requirement of anesthesia or nurse monitoring.16 One effective, safe, and tolerable alternative that has demonstrated real world effectiveness, and has become widespread in clinics across the United States, is rTMS.17 Multiple national guidelines and government agencies advocate for the use of rTMS to treat depression in patients with TRD who have failed just 1–2 antidepressant trials.18–21 The defining qualities of rTMS treatment make it a potential first-line treatment when pharmacotherapy has failed or is not an option: it is safe and tolerable, leads to minimal side effects, is easily delivered in an outpatient setting, and, while less efficacious than ECT, demonstrates real world response and remission rates conservatively estimated as approximately 60% and 30%, respectively.22,23 Additionally, a network meta-analysis revealed superior remission rates for rTMS compared to standard pharmacologic strategies at 4–6 week outcomes.24 The use of rTMS as a treatment for TRD is growing in acceptability, and future advances in the field are poised to broaden and enhance its role in treating MDD and other neuropsychiatric conditions.25–28 Given the above evidence and overall attractiveness of this treatment, it is surprising that many insurance companies remain overly cautious and hesitant in granting access to this treatment, some requiring class action lawsuits to motivate coverage for patients.29 Future studies investigating the place of rTMS within the TRD treatment algorithm will likely help solidify its use earlier in the course of illness.

There is evidence to suggest that many insurance companies overly restrict rTMS access for patients with TRD in the United States (see Supplementary Table 1 for details). Such overrestrictiveness through the prior authorization process includes requirements such as high disease severity, high number of failed antidepressant trials, and failed augmentation strategies and psychotherapy. With regard to high disease severity, the vast majority of existing evidence actually supports the use of rTMS in moderate and severe TRD rather than just severe illness.18,30 Two of the pivotal rTMS trials31,32 enrolled participants with an average moderate severity of depression, as measured by the 17-item and 24-item Hamilton Depression Rating Scales. This is in contrast to the requirement of moderate-severe or severe depression by many insurance companies (see Supplementary Table 1), for which there is no consistent method of measurement used by the industry. Multiple studies also show enhanced rTMS efficacy in patients with less treatment resistance, which contrasts with insurance companies’ demand of over 4 failed medication trials in many cases (Supplementary Table 1).33,34 In fact, the pivotal rTMS studies that led to FDA approval included only a minimum of 1–2 failed trials.23,31,32,35,36 Also, in a key network meta-analysis on rTMS in MDD that reviewed 81 trials and demonstrated the superiority of multiple forms of rTMS compared to sham, only 2 trials required failure of 3 or more medication trials, and none required 4 failed trials.37 Although effective in patients who have more than 3 failed medication trials, rTMS is most effective in patients with less treatment resistance.18,34,38 It is important to note here, though, that the standard for a failed pharmacotherapy trial can be more rigorous in the context of clinical trials than in regular clinical care. Beyond failed pharmacotherapy trials, there is no evidence to support the rationale for requiring failed psychotherapy prior to a trial of rTMS, and evidence does exist demonstrating that rTMS treatment can potentially lead to a reduction in the need for psychotherapy.39 Overall, while the above body of evidence clearly supports the use of rTMS as a treatment for TRD after failure of at most 2 antidepressant trials, the majority of insurance company health plans require severe depressive symptoms, at least 4 antidepressant medication trials from 2 different classes, and a course of psychotherapy before rTMS is considered for authorization. It is laudable that rTMS is available for patients with TRD with high disease severity and higher levels of treatment resistance, but access should not be restricted for patients with less disease severity and treatment resistance, for which the evidence shows rTMS is most effective.

The Clinical TMS Society (CTMSS) coverage guidance states that adults 18 years or older with a diagnosis of moderate or severe MDD with at least 1 failed antidepressant trial at an adequate dose and 6–8 week duration, or 2 not tolerated antidepressant trials at shorter duration, should be offered rTMS treatment.21,40 As a caveat, it is important to note that there is no consensus definition of a not tolerated antidepressant trial. The CTMSS guidance is not only rooted in the evidence, but also makes sense economically. Insurers are increasingly turning to incremental cost-effectiveness when examining new technologies or therapies for coverage. Incremental cost-effectiveness is commonly evaluated over the lifetime of a patient and examines the incremental cost of a new technology or therapy (eg, rTMS) versus standard of care (eg, pharmacotherapy), aggregating the incremental benefit as measured via quality of life (QoL). Aggregated QoL assessments measured over the life of a patient are termed quality-adjusted life-years (QALYs). In the US, the incremental cost-effectiveness ratio (ICER) is deemed cost-effective, and of good value, when the ICER is < $50,000/QALY gained.41 A recent analysis examining cost-effectiveness of rTMS after only 1 failed pharmacotherapy trial demonstrated that initiation of rTMS in younger (mid 20s) and older (mid 50s) patients yielded an incremental cost per QALY less than $50,000.42 Another study demonstrated that rTMS leads to higher QALYs and lower cost in TRD at both 3 and 5 years when compared to antidepressant treatment alone.43 This was shown even with conservative estimates of 37.5% response and 21.5% remission for rTMS. Another interesting coverage policy point is that there are at least 2 Medicare local carriers, Novitas Solutions (policy number L34998)44 and Noridian Healthcare Solutions (policy number L37086),45 that do cover the use of rTMS after treatment failure of at least 1 psychopharmacologic agent. Why other Medicare carriers and private insurers do not cover the use of rTMS after 1 trial is concerning, and it creates an access issue to a proven therapy.

Specialty society guidelines, upon which insurers generally rely to make coverage determinations, should be updated as it relates to the use of rTMS in MDD. The American Psychiatric Association (APA) clinical practice guidelines for MDD were last updated in 2010. The conclusion in these guidelines states, “Evidence for TMS is currently insufficient to support its use in the initial treatment of major depressive disorder.”46 In 2010, rTMS was being actively evaluated in clinical trials as to its clinical application and efficacy. It is now a proven therapy. The APA MDD clinical practice guidelines should be updated, as insurers commonly seek out the positions of specialty societies on various therapies when making coverage policies. Organizations such as the UK’s National Institute for Health and Care Excellence (NICE) support the use of rTMS in MDD in patients who have not responded to antidepressant medication or for whom antidepressants are not suitable. The NICE guidelines do not provide a specific number of failed medication trials, though.47 An update of this guideline in accordance with the CTMSS guidance would also be helpful for potential patients. Broader coverage and enhanced access for rTMS treatment will reduce morbidity and mortality for patients with TRD, improve cost-effectiveness of depression treatment, and relieve pressure on our burdened health care system. Health insurance plans should consider a revision of rTMS coverage policies accordingly. Advocacy and education initiatives directed at insurance companies by academic experts will help push this important agenda forward. Future studies that prospectively and comprehensively assess treatment algorithms for TRD may also help to highlight this rTMS coverage policy mismatch and lead to treatment optimization in TRD.

Published online: April 26, 2023.
Relevant financial relationships: Dr Weissman has served as a consultant for Goodcap Pharmaceuticals Inc. Dr Bermudes holds equity in TMS Health Partners, LLC, and receives royalties from American Psychiatric Association Publishing. Dr Liston has served as a scientific advisor or consultant to Compass Pathways PLC, Delix Therapeutics, and Brainify.AI. Dr Williams is a named inventor on Stanford-owned intellectual property relating to accelerated TMS pulse pattern sequences and neuroimaging-based TMS targeting; has served on scientific advisory boards for Otsuka, NeuraWell, Sooma, and Magnus Medical; and has equity/stock options in Magnus Medical, NeuraWell, and Sooma. Dr Blumberger receives research support from the Canadian Institutes of Health Research (CIHR), National Institutes of Health – US (NIH), Brain Canada Foundation and the Temerty Family through the CAMH Foundation and the Campbell Family Research Institute; received research support and in-kind equipment support for an investigator-initiated study from Brainsway Ltd. and was the site principal investigator for 3 sponsor-initiated studies for Brainsway Ltd; received in-kind equipment support from Magventure for investigator-initiated studies; received medication supplies for an investigator-initiated trial from Indivior; and has participated in advisory boards for Janssen and Welcony Inc. In the last 3 years, Dr Fitzgerald has received equipment for research from Neurosoft, Nexstim and Brainsway Ltd. He has served on scientific advisory boards for Magstim and LivaNova and received speaker fees from Otsuka. He has also acted as a founder and board member for TMS Clinics Australia and Resonance Therapeutics. Dr Daskalakis has received research and equipment in-kind support for an investigator-initiated study through Brainsway Inc and Magventure Inc and industry-initiated trials through Magnus Inc and currently serves on the scientific advisory board for Brainsway Inc. His work has been supported by the National Institutes of Mental Health (NIMH), the Canadian Institutes of Health Research (CIHR), Brain Canada, and the Temerty Family, Grant, and Kreutzcamp Family Foundations.  Dr Voigt reports no conflict of interest.
Funding/support: Dr Weissman is supported by a Brain and Behavior Research foundation Young Investigator Grant. Dr Fitzgerald is supported by a National Health and Medical Research Council of Australia Investigator grant (1193596).
Supplementary material: Available at Psychiatrist.com.

  1. Department of Psychiatry, University of California San Diego, La Jolla, California
  2. Corresponding author: Cory R. Weissman, MD, Department of Psychiatry, University of California San Diego, 9500 Gilman Dr, La Jolla, CA 92161 ([email protected]).
  3. Mindful Health Solutions, San Francisco, California
  4. Medical Device Consultants of Ridgewood, LLC, Ridgewood, New Jersey
  5. Department of Psychiatry, Brain and Mind Research Institute, Weill Cornell Medicine, New York, New York
  6. Stanford Brain Stimulation Laboratory, Stanford University, Stanford, California
  7. Temerty Centre for Therapeutic Brain Intervention, Campbell Family Research Institute, Centre for Addiction and Mental Health and Department of Psychiatry, Temerty Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
  8. Australian National University School of Medicine and Psychology, Canberra, Australia
  9. Department of Psychiatry, University of California San Diego, La Jolla, California
  1. Zhdanava M, Pilon D, Ghelerter I, et al. The prevalence and national burden of treatment-resistant depression and major depressive disorder in the United States. J Clin Psychiatry. 2021;82(2):20m13699. PubMed CrossRef
  2. Conway CR, George MS, Sackeim HA. Toward an evidence-based, operational definition of treatment-resistant depression: when enough is enough. JAMA Psychiatry. 2017;74(1):9–10. PubMed CrossRef
  3. Rush AJ, Trivedi MH, Wisniewski SR, et al. Acute and longer-term outcomes in depressed outpatients requiring one or several treatment steps: a STAR*D report. Am J Psychiatry. 2006;163(11):1905–1917. PubMed CrossRef
  4. McIntyre RS, Filteau MJ, Martin L, et al. Treatment-resistant depression: definitions, review of the evidence, and algorithmic approach. J Affect Disord. 2014;156:1–7. PubMed CrossRef
  5. Greden JF. The burden of disease for treatment-resistant depression. J Clin Psychiatry. 2001;62(suppl 16):26–31. PubMed
  6. Greenberg P, Corey-Lisle PK, Birnbaum H, et al. Economic implications of treatment-resistant depression among employees. Pharmacoeconomics. 2004;22(6):363–373. PubMed CrossRef
  7. Taipale H, Reutfors J, Tanskanen A, et al. Risk and risk factors for disability pension among patients with treatment resistant depression: a matched cohort study. BMC Psychiatry. 2020;20(1):232. PubMed CrossRef
  8. Greenberg PE, Fournier AA, Sisitsky T, et al. The economic burden of adults with major depressive disorder in the United States (2005 and 2010). J Clin Psychiatry. 2015;76(2):155–162. PubMed CrossRef
  9. Greenberg PE, Fournier AA, Sisitsky T, et al. The economic burden of adults with major depressive disorder in the United States (2010 and 2018). Pharmacoeconomics. 2021;39(6):653–665. PubMed CrossRef
  10. Riihimäki K, Vuorilehto M, Isometsä E. A 5-year prospective study of predictors for functional and work disability among primary care patients with depressive disorders. Eur Psychiatry. 2015;30(1):51–57. PubMed CrossRef
  11. Weissman CR, Hadas I, Yu D, et al. Predictors of change in suicidal ideation across treatment phases of major depressive disorder: analysis of the STAR*D data. Neuropsychopharmacology. 2021;46(7):1293–1299. PubMed CrossRef
  12. Bergfeld IO, Mantione M, Figee M, et al. Treatment-resistant depression and suicidality. J Affect Disord. 2018;235:362–367. PubMed CrossRef
  13. Rose D, Fleischmann P, Wykes T, et al. Patients’ perspectives on electroconvulsive therapy: systematic review. BMJ. 2003;326(7403):1363. PubMed CrossRef
  14. Lisanby SH, Maddox JH, Prudic J, et al. The effects of electroconvulsive therapy on memory of autobiographical and public events. Arch Gen Psychiatry. 2000;57(6):581–590. PubMed CrossRef
  15. Wilkinson ST, Agbese E, Leslie DL, et al. Identifying recipients of electroconvulsive therapy: data from privately insured Americans. Psychiatr Serv. 2018;69(5):542–548. PubMed CrossRef
  16. McIntyre RS, Rosenblat JD, Nemeroff CB, et al. Synthesizing the evidence for ketamine and esketamine in treatment-resistant depression: an international expert opinion on the available evidence and implementation. Am J Psychiatry. 2021;178(5):383–399. PubMed CrossRef
  17. Cohen SL, Bikson M, Badran BW, et al. A visual and narrative timeline of US FDA milestones for transcranial magnetic stimulation (TMS) devices. Brain Stimul. 2022;15(1):73–75. PubMed CrossRef
  18. McClintock SM, Reti IM, Carpenter LL, et al. National Network of Depression Centers rTMS Task Group; American Psychiatric Association Council on Research Task Force on Novel Biomarkers and Treatments. Consensus recommendations for the clinical application of repetitive transcranial magnetic stimulation (rTMS) in the treatment of depression. J Clin Psychiatry. 2018;79(1):35–48. CrossRef
  19. Milev RV, Giacobbe P, Kennedy SH, et al; CANMAT Depression Work Group. Canadian Network for Mood and Anxiety Treatments (CANMAT) 2016 clinical guidelines for the management of adults with major depressive disorder, section 4: neurostimulation treatments. Can J Psychiatry. 2016;61(9):561–575. PubMed CrossRef
  20. US Department of Veterans Affairs. VA/DoD Clinical Practice Guidelines: Management of Major Depressive Disorder. Published 2016. Accessed January 24, 2022. https://www.healthquality.va.gov/guidelines/MH/mdd/
  21. Perera T, George MS, Grammer G, et al. The Clinical TMS Society consensus review and treatment recommendations for TMS therapy for major depressive disorder. Brain Stimul. 2016;9(3):336–346. PubMed CrossRef
  22. Sackeim HA, Aaronson ST, Carpenter LL, et al. Clinical outcomes in a large registry of patients with major depressive disorder treated with transcranial magnetic stimulation. J Affect Disord. 2020;277:65–74. PubMed CrossRef
  23. Carpenter LL, Janicak PG, Aaronson ST, et al. Transcranial magnetic stimulation (TMS) for major depression: a multisite, naturalistic, observational study of acute treatment outcomes in clinical practice. Depress Anxiety. 2012;29(7):587–596. PubMed CrossRef
  24. Papadimitropoulou K, Vossen C, Karabis A, et al. Comparative efficacy and tolerability of pharmacological and somatic interventions in adult patients with treatment-resistant depression: a systematic review and network meta-analysis. Curr Med Res Opin. 2017;33(4):701–711. PubMed CrossRef
  25. Cole EJ, Phillips AL, Bentzley BS, et al. Stanford Neuromodulation Therapy (SNT): a double-blind randomized controlled trial. Am J Psychiatry. 2022;179(2):132–141. PubMed CrossRef
  26. Carmi L, Tendler A, Bystritsky A, et al. Efficacy and safety of deep transcranial magnetic stimulation for obsessive-compulsive disorder: a prospective multicenter randomized double-blind placebo-controlled trial. Am J Psychiatry. 2019;176(11):931–938. PubMed CrossRef
  27. Zangen A, Moshe H, Martinez D, et al. Repetitive transcranial magnetic stimulation for smoking cessation: a pivotal multicenter double-blind randomized controlled trial. World Psychiatry. 2021;20(3):397–404. PubMed CrossRef
  28. Leung A, Shirvalkar P, Chen R, et al; and the Expert Consensus Panel. Transcranial magnetic stimulation for pain, headache, and comorbid depression: INS-NANS expert consensus panel review and recommendation. Neuromodulation. 2020;23(3):267–290. PubMed CrossRef
  29. ABCS. Lawsuits, Aetna Insurance & Transcranial Magnetic Stimulation (TMS). 2019. Accessed February 23, 2023. https://abcsrcm.com/lawsuits-aetna-insurance-transcranial-magnetic-stimulation-tms/
  30. Voigt J, Carpenter L, Leuchter A. A systematic literature review of the clinical efficacy of repetitive transcranial magnetic stimulation (rTMS) in non-treatment resistant patients with major depressive disorder. BMC Psychiatry. 2019;19(1):13. PubMed CrossRef
  31. O’Reardon JP, Solvason HB, Janicak PG, et al. Efficacy and safety of transcranial magnetic stimulation in the acute treatment of major depression: a multisite randomized controlled trial. Biol Psychiatry. 2007;62(11):1208–1216. PubMed CrossRef
  32. George MS, Lisanby SH, Avery D, et al. Daily left prefrontal transcranial magnetic stimulation therapy for major depressive disorder: a sham-controlled randomized trial. Arch Gen Psychiatry. 2010;67(5):507–516. PubMed CrossRef
  33. Brakemeier EL, Luborzewski A, Danker-Hopfe H, et al. Positive predictors for antidepressive response to prefrontal repetitive transcranial magnetic stimulation (rTMS). J Psychiatr Res. 2007;41(5):395–403. PubMed CrossRef
  34. Trevizol AP, Downar J, Vila-Rodriguez F, et al. Predictors of remission after repetitive transcranial magnetic stimulation for the treatment of major depressive disorder: an analysis from the randomised non-inferiority THREE-D trial. EClinicalMedicine. 2020;22:100349. PubMed CrossRef
  35. Levkovitz Y, Isserles M, Padberg F, et al. Efficacy and safety of deep transcranial magnetic stimulation for major depression: a prospective multicenter randomized controlled trial. World Psychiatry. 2015;14(1):64–73. PubMed CrossRef
  36. Blumberger DM, Vila-Rodriguez F, Thorpe KE, et al. Effectiveness of theta burst versus high-frequency repetitive transcranial magnetic stimulation in patients with depression (THREE-D): a randomised non-inferiority trial. Lancet. 2018;391(10131):1683–1692. PubMed CrossRef
  37. Brunoni AR, Chaimani A, Moffa AH, et al. Repetitive transcranial magnetic stimulation for the acute treatment of major depressive episodes: a systematic review with network meta-analysis. JAMA Psychiatry. 2017;74(2):143–152. PubMed CrossRef
  38. Hsu JH, Downar J, Vila-Rodriguez F, et al. Impact of prior treatment on remission with intermittent theta burst versus high-frequency repetitive transcranial magnetic stimulation in treatment resistant depression. Brain Stimul. 2019;12(6):1553–1555. PubMed CrossRef
  39. Needs P, Mote SD, Manocchia M, et al. Psychotherapy and psychopharmacology utilization following repetitive transcranial magnetic stimulation (rTMS) in patients with major depressive disorder. Psychiatry Res. 2019;278:51–55. PubMed CrossRef
  40. Clinical TMS Society. Coverage Guidance for Transcranial Magnetic Stimulation (TMS) for Major Depressive Disorder (MDD). May 3, 2021. https://www.clinicaltmssociety.org
  41. Anderson JL, Heidenreich PA, Barnett PG, et al. ACC/AHA statement on cost/value methodology in clinical practice guidelines and performance measures: a report of the American College of Cardiology/American Heart Association Task Force on Performance Measures and Task Force on Practice Guidelines. J Am Coll Cardiol. 2014;63(21):2304–2322. PubMed CrossRef
  42. Voigt J, Carpenter L, Leuchter A. Cost effectiveness analysis comparing repetitive transcranial magnetic stimulation to antidepressant medications after a first treatment failure for major depressive disorder in newly diagnosed patients: a lifetime analysis. PLoS One. 2017;12(10):e0186950. PubMed CrossRef
  43. Nguyen KH, Gordon LG. Cost-effectiveness of repetitive transcranial magnetic stimulation versus antidepressant therapy for treatment-resistant depression. Value Health. 2015;18(5):597–604. PubMed CrossRef
  44. Novitas Solutions. Policy number: L34998. Repetitive transcranial magnetic stimulation (rTMS) in adults with resistant major depressive disorder. LCD - Repetitive Transcranial Magnetic Stimulation (rTMS) in Adults with Treatment Resistant Major Depressive Disorder (L34998). Accessed January 31, 2023. https://www.cms.gov/medicare-coverage-database/view/lcd.aspx?lcdId=34998&ver=28
  45. Noridian Healthcare Solutions. Policy number: L37086. Repetitive transcranial magnetic stimulation (rTMS) in adults with resistant major depressive disorder. LCD - Repetitive Transcranial Magnetic Stimulation (rTMS) in Adults with Treatment Resistant Major Depressive Disorder (L37086). Accessed January 31, 2023. https://www.cms.gov/medicare-coverage-database/view/lcd.aspx?LCDId=37086
  46. Gelenberg A, Freeman MP, Markowitz JC, et al. Practice Guideline for the Treatment of Patients With Major Depressive Disorder, Third Edition. American Psychiatric Association; 2010.
  47. National Institute for Health and Care Excellence. Repetitive transcranial magnetic stimulation for depression. Interventional procedures guidance [IPG542]. Healthcare Improvement Scotland. Published December 16, 2015. https://www.nice.org.uk/guidance/ipg542