Positioning of Esketamine Treatment (PoET) in the real-world management of depression

Depression is a common mental illness, and it is one of the leading causes of disease burden worldwide. Fortunately, there are many effective treatments available for depression, including lifestyle changes, psychological treatments, and medications such as antidepressants. However, not all patients will respond to the first treatment prescribed. Some patients may only experience a 'partial response', where a few treatments help their depression somewhat, but they do not achieve a full recovery. Currently, the reasons why some patients do not respond, or only experience a partial response to an antidepressant, is not fully understood. Recently, researchers have been investigating new medications that may help patients recover from depression. One of these new medications is Esketamine, which is a relatively new molecule derived from a drug called Ketamine - an anaesthetic that has been used medically for decades. Researchers have been investigating the antidepressant properties of Ketamine for a long time. It is thought that Ketamine, and its derivative, Esketamine, help to treat depression for a number of reasons. However, it is not yet known which patients benefit most from Esketamine when used in conjunction with conventional antidepressants. In addition, we do not yet understand how the effect of Esketamine is impacted by other treatments that a patient may be taking for their depression. Finally, it has not yet been investigated how patients with a partial response to an antidepressant will benefit from adding Esketamine to their therapeutic regimen without switching to a new baseline antidepressant. Therefore, there are two principle aims of this study 1) to investigate whether Esketamine is effective when added to ongoing antidepressant treatment and 2) to identify patient characteristics that will determine a therapeutic response to Esketamine in real-world practice. In patients that improve with the addition of Esketamine to their current antidepressant treatment, we hypothesize that their improvement will be determined by their personal characteristics and/or the type of treatment they are already receiving.