Pharmacogenomic-Guided Prescribing and Polypharmacy Across Age Groups in Obsessive-Compulsive Disorder: A Retrospective Study

Background This study evaluated medication utilization in children, adolescents, and adults with obsessive-compulsive disorder (OCD), a chronic psychiatric condition characterized by intrusive thoughts and repetitive behaviors. Although first-line treatments include selective serotonin reuptake inhibitors (SSRIs) and cognitive behavioral therapy (CBT), the heterogeneous biological underpinnings contribute to suboptimal outcomes, with 40–60% of individuals not responding to SSRIs. This complex phenotype often leads to psychotropic polypharmacy, which may be mitigated by incorporating combinatorial pharmacogenomic (PGx) testing into protocol-based care to identify potential gene-drug interactions. Methods A retrospective review was conducted of individuals with OCD aged 8 to 65 years who received either PGx testing or treatment as usual (TAU). Co-primary outcomes were polypharmacy rate and quality of life. Secondary outcomes included length of stay, medication utilization, and OCD and depression severity. Individuals prescribed at least one daily psychotropic medication with a gene-drug interaction were classified as “incongruent” (PGx-I). Individuals without gene-drug interactions for all prescribed psychotropic medications were categorized as “congruent” (PGx-C). Results A total of 363 individuals with OCD were analyzed. Of these 241 received TAU and 122 underwent PGx testing. Within the PGx cohort, 67% were prescribed medications with potential gene-drug interactions at discharge. The polypharmacy rate was 71% in the PGx-I cohort, compared with 35% in the PGx-C cohort. Quality-of-life measures revealed similar levels of improvement in the PGx-C and PGx-I cohorts. Conclusions Psychotropic polypharmacy rates were higher among individuals prescribed at least one medication with a gene-drug interaction, most notably among adults, while all cohorts showed similar improvement. These findings suggest that incorporating combinatorial PGx testing into the medical evaluation particularly where polypharmacy is a concern may help optimize medication selection, while maintaining effectiveness.