Who receives psychiatry-focused pharmacogenomic testing, and is it associated with prescribing patterns and acute care utilisation in depression? Real-world evidence from a large health system.

Abstract

Depression is highly prevalent, and antidepressant response and tolerability vary widely. Pharmacogenomic (PGx) testing is increasingly used to support antidepressant selection, but its real-world uptake, equity, and associations with prescribing and healthcare utilisation remain incompletely characterised. Using electronic health record data from a large health system (2013-2023), we identified 1563 patients with depression who received psychiatry-focused PGx testing and compared them with 248,017 indexed non-PGx controls. We examined demographic and clinical factors associated with receipt of PGx testing, evaluated changes in antidepressant and adjunctive psychiatric medication use pre/post-testing using within-person and difference-in-differences analyses with propensity-score-matched controls. Associations between PGx testing and acute care utilisation, including emergency department (ED) visits and hospitalisations, were examined. PGx testing was more common among youth and adults with complex clinical histories but less frequent among older adults and racially minoritized groups; Black, American Indian/Alaska Native, and Asian/Native Hawaiian/Other Pacific Islander patients had 55-65% lower odds of testing than patients identifying as White. Testing clustered among individuals with greater psychiatric comorbidity burden and prior antidepressant trials. Following testing, antidepressant prescribing patterns shifted away from CYP2C19/2D6-sensitive SSRIs and toward agents less dependent on these pathways. Adjunctive anxiolytic and hypnotic prescribing showed modest pre/post declines but these patterns did not significantly differ compared to matched controls. Psychiatric ED visits showed no significant overall difference-in-differences association with PGx testing when compared with matched controls, although exploratory sensitivity analyses suggested a signal of reduced ED utilisation among patients with higher baseline psychiatric complexity. Hospitalisation patterns showed no substantial change. In routine clinical practice, PGx testing is preferentially used in youth and adults with clinically complex histories and is associated with shifts in antidepressant prescribing patterns. Exploratory findings suggest hypothesis-generating signals of reduced psychiatric ED utilisation among patients with higher psychiatric complexity, which requires further confirmation. Observed racial disparities highlight the need for earlier and more equitable implementation. Prospective studies incorporating symptom-level and safety outcomes are needed to determine whether PGx-guided prescribing translates into meaningful clinical benefit. Supported by NIH (UL1TR002494), American Association of Psychiatric Pharmacists Foundation and University of Minnesota College of Pharmacy.