A Standard of Care Study of Patients With Major Depressive Disorder Who Have Had an Inadequate Response to a Selective Serotonin Reuptake/Serotonin-Norepinephrine Reuptake Inhibitor Antidepressant

Inclusion Criteria

• •Has a diagnosis of Major Depressive Disorder (MDD) without psychotic features as confirmed by the Mini International Neuropsychiatric Interview (MINI)
• •Treatment with an selective serotonin reuptake inhibitor (SSRI)/serotonin-norepinephrine reuptake inhibitor (SNRI) for at least 6 weeks at an adequate dose (per Massachusetts General Hospital-Antidepressant Treatment Response Questionnaire \[MGH-ATRQ\]). Specifically, one of the following in any formulation is allowed: SSRIs: citalopram, duloxetine, escitalopram, fluvoxamine, fluoxetine, milnacipran, levomilnacipran, paroxetine, sertraline; SNRIs: venlafaxine, desvenlafaxine, vilazodone, or vortioxetine
• •In the opinion of the treating clinician, the participant requires augmentation of the current antidepressant treatment and plans to initiate augmentation treatment in the near future. The participant has agreed to receive augmentation treatment
• •Is currently an outpatient receiving psychiatric care (not inpatient care settings)
• •Has a body mass index (BMI) of 18-40 kilograms per meter square (Kg/m\^2), inclusive