PurposeMajor depressive disorder (MDD) is a chronic mental disorder with a substantial clinical and economic burden. Despite the efficacy of adjunctive atypical antipsychotics (AAP) for augmentation in patients with major depressive disorder (MDD) who failed first-line antidepressant therapy (ADT), little is known of the impact of AAP choices on healthcare resource use and costs in real-world practice. Therefore, this study compared real-world healthcare utilization and costs in patients with MDD treated with brexpiprazole or extended-release (XR) quetiapine as adjunctive treatment to ADT.Patients and methodsAdults with MDD starting adjunctive treatment with brexpiprazole (n=844) or extended-release (XR) quetiapine (n=688) were identified in the adjudicated health plan claims data (07/2014 – 09/2016). Resource use and healthcare costs in the 6 months following treatment initiation were compared between non-matched populations, and between propensity score-matched groups, and by multivariable regression analyses.ResultsDuring follow-up, unadjusted all-cause hospitalization (6.6% vs 12.5%) and ED visits (17.0% vs 27.5%) were lower with brexpiprazole compared to quetiapine XR (both p<0.001). Brexpiprazole-treated patients had significantly lower mean medical costs (US$6,421 vs US$8,545, p=0.0123) but higher mean pharmacy costs (US$7,401 vs US$4,691, p<0.0001) than quetiapine XR-treated patients did. Total healthcare costs were not significantly different between the two cohorts. Propensity score-matched comparisons of 397 patients in each cohort showed no statistically significant difference in all-cause hospitalization, ED visits, and total healthcare costs; and significantly lower medical costs (US$5,719 vs US$8,602, p=0.0092) but higher pharmacy costs (US$7,091 vs US$5,091, p=0.0007) in brexpiprazole compared to quetiapine XR. In multivariable regressions, brexpiprazole was associated with 16.1% lower medical costs (p=0.0186) and 9.4% higher total healthcare costs (p=0.0463) as compared to quetiapine XR.ConclusionSignificantly lower medical costs were observed in patients with MDD treated with brexpiprazole vs quetiapine XR.