Insights Into Patient-Level Exposure to Actionable Pharmacogenomic Medications in Australia Using a New National Pharmacogenomic Guideline.

This study assessed the use of 35 pharmacogenomic (PGx) medications listed in the Royal College of Pathologists of Australasia (RCPA) guideline, estimated the potential costs of subsidizing PGx testing in Australia, and predicted related prescribing changes. Using administrative claims data from the Pharmaceutical Benefits Scheme, accessed via the Australian Bureau of Statistics DataLab, we identified individuals who received any of the 35 medications between January 2021 and December 2023. Incident prescribing rates were calculated for children (0-17), adults (18-64), and older adults (65+). Adults (14.91%) and older adults (14.44%) had the highest rates of PGx medication use, followed by children (3.53%). Commonly prescribed medications included proton pump inhibitors, with frequent associations to genes such as CYP2C19 across all age groups. Estimated costs of PGx testing, assuming 50% and 75% population uptake, were highest for older adults: AUD$1.95 million and AUD$2.93 million, respectively. Predicted prescribing changes, based on literature-reported phenotype frequencies by ancestry, suggested that up to 18.58% of individuals using drugs like clopidogrel or voriconazole may need alternative treatments due to poor metabolism. These findings highlight the clinical potential of integrating PGx testing into routine practice, especially for medications included in international pharmacogenomic guidelines. While implementation would entail significant upfront costs, PGx testing could enhance medication safety and effectiveness and health care cost-efficiency. Future research should focus on scalable strategies for PGx implementation across diverse health care settings to optimize patient care globally.