Medication adherence following pharmacogenomic testing in patients with major depressive disorder

Approximately 50% of patients with major depressive disorder (MDD) prematurely discontinue their antidepressant medication within 6 months, increasing risk of relapse. Pharmacogenomic (PGx) testing may improve medication adherence by informing treatment based on gene-drug interactions (GDI). Here, we evaluated whether PGx informed treatmentimproved medication adherence in MDD patients.

This was an observational, retrospective claims study of adult MDD patients who received a weighted multi-gene PGx test between 1 Jan 2015 and 30 September 2021 and switched medication. PGx results were linked with de-identified administrative claims data from the Optum Labs Data Warehouse. The PGx test report organized psychiatric medications into three categories: no known GDI (congruent), moderate GDI (congruent), and significant GDI (incongruent). Patients were assigned to the following groups based on the medication with the worst congruency 90 days pre- and post-PGx testing: incongruent-to-congruent, no-change-in-congruency, and congruent-to-incongruent. Medication adherence (proportion of days covered [PDC]) and discontinuation (a ≥ 45-day gap in medication fills) were assessed using pharmacy fill data during the 180 days following the date of medication switch (index date).

Among 6224 patients with PGx testing, those in the incongruent-to-congruent group had the highest adherence (mean PDC 0.65, SD 0.33), compared to the congruent-to-incongruent (mean PDC 0.58, SD 0.34) (p < 0.05) and no-change-in-congruency groups (mean PDC 0.61, SD 0.34) (p < 0.05). The incongruent-to-congruent group also had the lowest discontinuation rate (46%) compared to the congruent-to-incongruent (55%) (p < 0.05) and no-change-in-congruency groups (50%) (p < 0.05).

Using PGx informed medication selection can improve medication adherence and reduce discontinuation among MDD patients.