Prevalence of pharmacogenomically implicated prescriptions in multi-ethnic populations in Singapore

To assess the potential impact of implementing pre-emptive pharmacogenomic (PGx) testing in Singapore, focusing on prevalence and genetic actionability of PGx prescriptions.

Electronic Health Records from 2014 to 2021 were obtained from the National University Hospital (NUH), a tertiary medical centre serving approximately 6% of Singapore's population, which were filtered for pharmacogenomically implicated medicines (CPIC Level A or A/B), defined as PGx medications. Coupling this with published data of whole-genome sequencing of 9051 Singaporeans, we estimated the proportion of patients whose prescriptions might have been modified based on pre-emptive PGx at population level.

From 2014 to 2021, a total of 1 157 359 unique patients were seen at NUH, with 38.1% to 43.0% of patients with prescriptions receiving at least one PGx medication annually, exhibiting minimal variance over year of prescription, sex or race/ethnicity. The most frequently prescribed PGx medications were omeprazole, statins and tramadol, while the most implicated pharmacogenes were CYP2C19, CYP2D6 and SLCO1B1. The age-dependent increase in PGx medication exposure varied significantly by sex, with males prescribed these medications earlier in life than females. Similarly, Indians and Malays were more likely to be prescribed these medicines at a younger age than Chinese. Based on frequency of PGx variants in Singaporeans, we estimate that 18.4% of patients could have their prescriptions modified from pre-emptive PGx testing.

Pharmacogenomically implicated medication prescriptions are common in Singapore and are particularly prevalent in elderly populations. Strategic investments in infrastructure and policy development will be pivotal to the successful integration of pre-emptive PGx into clinical practice.