An episode level evaluation of the treatment journey of patients with major depressive disorder and treatment-resistant depression

BACKGROUND: Many patients with major depressive disorder (MDD) fail to respond to antidepressant (AD) pharmacotherapy. The objectives of this study were to characterize MDD and treatment-resistant depression (TRD) at the level of pharmacologically treated episodes and to describe the sequential treatment patterns by lines of therapy (LOT) in the first two episodes. METHODS: Adults (≥18 years of age) with continuous enrollment ≥12 months before and after the first MDD diagnosis and treated with an AD, with or without an MDD-indicated antipsychotic (AP), were identified (1/1/2010-12/31/2015). The MDD episode started on the date of MDD diagnosis that was preceded by a clean period without any MDD diagnosis. The MDD episode ended on the last MDD diagnosis or the end of the days’ supply of AD/AP medication, whichever came last. TRD was defined as an MDD episode with ≥3 AD/AP regimens. Measured outcomes included episode duration, number of LOT, relapse hospitalization, and sequential treatment patterns of MDD episode stratified by TRD and non-TRD episodes. RESULTS: Of 48,440 patients who received AD/AP in the 1(st) MDD episode, 3,317 (6.8%) of episodes were considered TRD. Mean duration of 1(st) TRD episodes was 571 days, mean number of AD/AP LOTs was 3.47, and 13.7% involved relapse hospitalization. Mean duration of 1(st) non-TRD episodes was 200 days, mean number of AD/AP LOTs was 1.21, and 9.6% involved relapse hospitalization. Among 1(st) MDD episodes, 25.5% had a second LOT; 7.3% had a third LOT. Most patients received selective serotonin reuptake inhibitors (SSRIs) as the first LOT (63.0%), and the plurality of regimens were SSRIs in second (44.9%) and third LOT (41.1%). CONCLUSIONS: Compared to non-TRD episodes, TRD episodes were longer and more often involved relapse hospitalizations. SSRIs were the most common treatment; treatment changes and potential treatment unresponsiveness were frequent among MDD patients.