MedicalResearch.com with: [caption id="attachment_68093" align="alignleft" width="152"] Luke Cavanah B.S.[/caption] Luke Cavanah, BS Department of Medical Education Geisinger College of Health Sciences Scranton, PA, 18509 MedicalResearch.com: What is the background for this study? Response: Almost a third of patients with medication-treated major depressive disorder will fail at least two depressants—many patients failing more.¹ Esketamine is an intranasal medication that was FDA-approved in 2019 for such patients when used in conjunction with an oral antidepressant.² Esketamine also is unique from the more traditional oral antidepressants in its mechanism of action, quick onset, and evidence for treatment of acute suicidality.³ While esketamine has been of much interest for these last few years, a recent study found low and geographically variable use of this medication within the Medicaid population.⁴ We were interested in investigating esketamine treatment utilization among Medicare patients in 2019 and 2020.