Incorporating a standardized approach to evaluate the clinical utility of pharmacogenetic testing could increase its inclusion and consistency in clinical practice, according to research published in the American Journal of Health-System Pharmacy.1 The authors of the study said that the use of pharmacogenetic testing could benefit both patients and society as a whole.
Pharmacogenetic testing is a type of precision medicine that looks at how gene polymorphisms impact the function of drug metabolizing proteins.2 Understanding these gene-drug interactions can help with appropriate treatment of chronic diseases and prevent a majority of drug-related hospitalizations.3 However, defining what is sufficient evidence of clinical utility to recommend pharmacogenetic testing has been debated.
Key Takeaways
- The study highlights the need for a standardized approach to evaluating the clinical utility of pharmacogenetic testing to resolve inconsistencies among clinical practice guidelines.
- Inconsistencies in testing recommendations among clinical associations contribute to the limited uptake of pharmacogenetic testing in clinical practice. Standardizing the evaluation of evidence for clinical utility could help alleviate these discrepancies and provide clearer guidance for healthcare providers.
- Establishing consistent recommendations for pharmacogenetic testing has the potential to improve patient outcomes by ensuring appropriate treatment and reducing the risk of adverse drug reactions. This standardized approach could lead to more widespread use of pharmacogenetic testing.
“The lack of consensus on the level and type of evidence of clinical utility needed to recommend pharmacogenetic testing has led to confusion as to which pharmacogenetic tests should be used in clinical practice,” the authors wrote. “There is variability in testing recommendations by clinical society and the Food and Drug Administration (FDA) and in coverage by payors. This inconsistency is partly due to differences in the types of recommendations and evidence required for each.”
A team of investigators from the Standardizing Laboratory Practices in Pharmacogenomics (STRIPE) Collaborative Community’s Study Designs Task Force (SDTF) conducted a narrative review to describe the current status of pharmacogenetic testing recommendations within clinical practice guidelines in the United States. A systematic search of clinical practice guidelines from established clinical associations was conducted to identify and review gene-drug pairs with guidelines from the Clinical Pharmacogenetic Implementation Consortium.
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Clinical practice guidelines on pharmacogenetic testing for 21 gene-drug pairs were categorized into 5 therapeutic areas, including pain and general medicine; infectious disease; psychiatry and neurology; and oncology. Information on pharmacogenetic testing gene-drug pair, year, testing recommendations, and any evidence used to support the recommendation was collected from the guidelines and was used to identify areas of inconsistency among the associations.
Investigators found that there were not many clinical practice guidelines among the associations that recommended pharmacogenetic testing. When there were testing recommendations for a gene-drug pair, they were often inconsistent between the associations, and were sometimes even inconsistent from different guidelines provided by the same association.
“[There were] limited examples of pharmacogenetic testing requirements or recommendations in clinical practice guidelines, which likely contributes to the lack of uptake of pharmacogenetic testing in clinical practice,” the authors wrote.
The study did find that some pharmacogenetic testing recommendations were consistent between the associations, such as testing for the HLA-B*57:01 genotype before starting treatment with abacavir (Ziagen) and testing for the G6PD genotype before starting treatment with rasburicase (Elitek). Additionally, gene-drug pairs with at least 1 clinical practice guideline recommending testing included CYP2C19-clopidogrel, CYP2D6- codeine, CYP2D6-tramadol, CYP2B6-efavirenz, TPMT-thiopurines, and NUDT15-thiopurines.
Study limitations include that not all gene-drug pairs were included, that only clinical practice guidelines that mentioned pharmacogenetic testing were reviewed, and that some clinical practice guidelines that were included may not have been the most recent literature.
“A standardized approach to evaluating the evidence of clinical utility of pharmacogenetic testing may increase the inclusion and consistency of pharmacogenetic testing recommendations in clinical practice guidelines,” the authors concluded. “Consistent recommendations for pharmacogenetic testing in clinical practice guidelines would likely increase the clinical use of pharmacogenetic testing, which could improve patient outcomes and benefit society by preventing unnecessary, unsafe, and ineffective treatment.”
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References
1. Hertz DL, Bousman CA, McLeod HL, et al. Recommendations for pharmacogenetic testing in clinical practice guidelines in the US. Am JHealthSyst Pharm. 2024; zxae110. https://doi.org/10.1093/ajhp/zxae110
2. Young C, MacDougall D. An Overview of Pharmacogenomic Testing for Psychiatric Disorders: CADTH Horizon Scan [Internet]. Ottawa (ON): Canadian Agency for Drugs and Technologies in Health; 2023 Jun. Available from: https://www.ncbi.nlm.nih.gov/books/NBK595332/
3. O’Shea J, Ledwidge M, Gallagher J. et al. Pharmacogenetic interventions to improve outcomes in patients with multimorbidity or prescribed polypharmacy: a systematic review. Pharmacogenomics J 22, 89–99 (2022). https://doi.org/10.1038/s41397-021-00260-6
