(SLB-057) Exposure to multiple drugs with actionable pharmacogenetic biomarkers among older adults in China: A retrospective analysis

Background: The introduction of pharmacogenetic (PGx) testing presents a promising solution, offering a more precise and personalized approach to medication management for older individuals with polypharmacy. It is crucial to investigate the prevalence of longitudinal exposure to multiple genetically related drugs to improve drug efficiency and minimize the incidence of adverse drug reactions (ADRs) in the elderly population.

Objectives: To investigate the prevalence of longitudinal exposure to multiple drugs with a high level of evidence (Level A) for pharmacogenetic-guided drugs (PGx drugs) among older adults, determine the prevalence of genes associated with PGx drugs (pharmacogenes), and assess the cumulative impact of these gene-drug pairs to health resource utilizations.

Methods: This cross-sectional study analyzed data from 2015 to 2017, encompassing individuals aged 65 years and older within the China Health Insurance Research Association (CHIRA). We identified 53 drugs with the highest level of evidence for actionable pharmacogenetic variants, according to the Clinical Pharmacogenomics Implementation Consortium (CPIC) guidelines, as of January 1, 2024. The study estimated the prevalence of older adults exposed to at least two or at least five CPIC Level A drugs within the same calendar year. Among those exposed to multiple PGx drugs, drugs were categorized by their associated pharmacogenes, and the prevalence for each category was ascertained. Subsequently, the cumulative impact of these pharmacogenes was calculated based on these prevalence figures.

Results: Between 2015 and 2017, 20.2% older patients were prescribed at least 2 CPIC level A drugs, and 1.9% were prescribed five or more. Among those prescribed at least two CPIC level A drugs, atorvastatin was the most prevalent, affecting 84.2 per 1000 patients. For patients receiving at least five level A drugs, the proton pump inhibitor (PPI) pantoprazole was the most common, with a rate of 11.9 per 1000 patients. Our data underscore that the most relevant pharmacogenes for use in testing panel are CYP2C19, SLCO1B1, and CYP2C9 in the population exposed exposed to multiple CPIC level A drugs. These three pharmacogenes are relevant for over 95% of older patients.

Conclusions: Exposure to multiple drugs with actionable pharmacogenetic biomarkers among older people is common. A small number of pharmacogenes account for the majority of the population exposed to multiple pharmacogenomic drugs. This finding suggests that PGx testing of specific multi-exposed gene-drug pairs should be considered for frequently prescribed PGx drugs and their implicated genes to optimize prescribing among elders.