|
Knowledge and Attitudes about Pharmacogenetic Testing Among Clinicians & Patients (Van Riper, Evans, Kaufman; Howard McLeod, CGS Genome Sciences Collaborator)
Significance: Notable advances have occurred in the integration of pharmacogenetics into clinical practice. For example, the FDA has recently revised the drug labeling for mercaptopurine, azathioprine, and irinotecan to include pharmacogenetic dosing and safety information. The FDA Subcommittee on Clinical Pharmacology has also recommended addition of pharmacogenetics information to identify risk of toxicity or therapeutic failure for the commonly used medications warfarin and tamoxifen. As affordable, high throughput-technologies are increasingly available, scale-up is likely to occur in genotype-guided drug therapy. That is, rather than ordering a single pharmacogenetic test to determine how patients will respond to a specific drug, clinicians will be able to order a panel of tests or a whole-genome scan to determine how patients will respond to a wide variety of drugs. Despite these advances in our ability to use genetic information to guide drug therapy, there are many ELSI issues that need to be resolved before pharmacogenetics becomes a routine part of clinical practice. These issues include concerns about privacy; confidentiality; informed consent; cost; equity of access to possibly expensive treatments; genetic testing of children for potential future drug reactions; the use and storage of genetic information and drug response data in large data sets or registries; marketing of race-based pharmacogenetics, and duty to warn of possible genetic risk for adverse drug reactions in direct-to-consumer marketing.
Rogausch and colleagues argue that future implementation of pharmacogenetics in daily medical practice will ultimately depend upon patients’ and physicians’ acceptance of, and requests for, this type of testing. Currently, little is known about attitudes towards and understanding of pharmacogenetic testing among clinicians and patients. One of the few existing studies by Rogausch and colleagues suggests that attitudes and concerns about pharmacogenetic testing often differ between patients and physicians. They found that while patients were primarily concerned with privacy issues and adverse treatment by employers or insurance company, physicians were concerned that employers or insurance companies might pressure patients into pharmacogenetic testing, and patients might be disadvantaged if a testing showed a need for very high doses of a drug.
The recently established Institute for Pharmacogenetics and Individualized Therapy (IPIT) at UNC (directed by Howard McLeod), is a multidisciplinary center that constitutes one of 10 funded sites in the NIH Pharmacogenetics Research Network. The IPIT has launched an initiative to integrate genetic testing to optimize therapy in routine clinical practice, focusing on integrating genotypic data to guide the dosing of warfarin at UNC. Warfarin is an oral anticoagulant, one of the most commonly prescribed drugs in the US, yet its management is especially challenging due to wide variations in doses required to achieve a therapeutic effect. Using genotype-guided anticoagulant therapy, clinicians can estimate the therapeutic dose by identifying single nucleotide polymorphisms that affect warfarin metabolism. Implementation of pre-prescription genotyping and individualized warfarin therapy represents an opportunity to minimize the risk of life-threatening complications without compromising effectiveness. Currently, the FDA is updating the guidelines for the dosing of warfarin and has indicated support for the use of genotype-guided dosing to improve the safety of this drug. This project has two research questions:
Research Question 1: What is patients’ and clinicians’ knowledge about pharmacogenetic testing and how does this change overtime?
Research Question 2: What are clinicians’ and patients’ hopes, concerns, and expectations regarding pharmacogenetic testing?
Outcomes: Establishment of a pharmacogenetic testing initiative in the anticoagulation clinic at UNC will not only help to improve anticoagulation-related outcomes for patients on warfarin, it will help in the identification of best practices for implementing pharmacogenetics in a more general fashion as more clinically useful testing is developed. Acceptance of, and requests for, pharmacogenetic testing by clinicians and patients will play a critical role in its success. Project findings on patients’ and clinicians’ knowledge, hopes, concerns, and expectations and how these compare between the two groups will inform clinical practice as pharmacogenetic testing becomes broadly integrated into routine medical care.
|
