Abstract
The aim of this study was to describe self-reported use of medications with established pharmacogenetic guidance in the Our Future Health (OFH) cohort. We examined four key pharmacogenes-CYP2C19, CYP2C9, CYP2D6, and SLCO1B1-and medications supported by strong evidence for clinical actionability according to the Clinical Pharmacogenetics Implementation Consortium (CPIC). Self-reported medication use was summarized, concurrent use assessed, and findings stratified by age, sex, and ethnicity. We studied these data in 1.78 million OFH participants included in the June 2025 release. The cohort was 57.3% female, aged 18-95 years (mean 53.1 years), with 90.2% self-identifying as "White." Eighteen medication groups were explicitly listed in the baseline questionnaire, enabling identification of exposure at group level rather than for individual drugs. Medication groups with pharmacogenetic relevance included antidepressants (selective serotonin reuptake inhibitors and tricyclics), statins, proton pump inhibitors, ibuprofen, opioids, clopidogrel, and warfarin. Overall, 25.2% of participants (N = 449,641) reported use of at least one such group. These users tended to be older, more frequently female, and reported more comorbidities than non-users. Concurrent exposure to two or more pharmacogenetically actionable medications metabolized by different genes was common, occurring in 37% of users. A substantial proportion of the OFH cohort therefore reported exposure to medications with pharmacogenetic guidance. Use was observed across all ages, with prevalence increasing with age. With continued expansion of the cohort and future linkage to prescribing records, OFH will provide a critical resource for population-scale pharmacogenetic research.