Opportunities for Pharmacogenetic Testing Among Hospitalized Children With Medical Complexity

Children with medical complexity (CMC), in whom drug efficacy and adverse drug events are difficult to assess, could benefit from pharmacogenetic (PGx) testing. We sought to determine the prevalence of prescribed medications with a high level of evidence for PGx-guided dosing and to identify their associated genes for testing among CMC.

This cross-sectional study included patients discharged from a complex care inpatient team from June 2019 to June 2020. We identified medications with level A evidence for PGx-guided dosing per the Clinical Pharmacogenetics Implementation Consortium (CPIC) in January 2023 (N = 73) from medication lists. We determined frequency of CPIC level A scheduled and as-needed (PRN) prescriptions. We compared these findings with a secondary dataset of patients who attend a complex care clinic.

For CPIC level A medications prescribed to the inpatients, 60.2% were on at least 1 scheduled medication and 60.2% were on at least 1 PRN medication. The most commonly scheduled medications were lansoprazole (25.0%) and omeprazole (16.4%); the most common PRN medications were ibuprofen (50%), ondansetron (18.8%), and tramadol (3.9%). The outpatient cohort similarly had a large proportion on at least 1 scheduled or 1 PRN medication (44.4% and 47.6%, respectively), with proton pump inhibitors (PPIs) being commonly prescribed. The genes most highly associated with the medications prescribed to both populations were CYP2C19, CYP2C9, and CYP2D6.

PPIs were the most common CPIC level A medications and are metabolized by CYP2C19, making it the most highly implicated gene. PPI-CYP2C19 should be a PGx testing priority.