Encountering Pharmacogenomic Test Results in Psychiatry
Precision medicine, using pharmacogenomic testing, can streamline the process of finding the right treatment for each patient’s depression and result in better outcomes. Pharmacogenomics, also called pharmacogenetics or PGx, facilitates a personalized prescribing approach that utilizes a person’s genetic information to inform medication selection and dosing decisions. While some physicians will feel comfortable providing consults, managing, and perhaps integrating the genetic test results into their practice, many will feel unsure about the merits of pharmacogenomics or how to interpret and act on the results. A recent publication in The Canadian Journal of Psychiatry, “Encountering Pharmacogenetic Test Results in the Psychiatric Clinic,” addresses common concerns and offers strategies and resources to prepare psychiatrists for patient care situations where genetic test results are encountered.
How to assess the validity of a pharmacogenomic test
Pharmacogenomic tests offered by various providers are not equivalent or interchangeable. Look for three test characteristics that, when present, can boost confidence in the results provided.
- The laboratory performing the test should be accredited.
- The pharmacokinetic genes and alleles tested as directly associated with medication exposure and tolerability. The test should include both Tier 1 and Tier 2 alleles as per guidelines for CYP2C19 and CYP2D6 genes. Including more alleles increases the test’s the sensitivity and specificity of the PGx test, making it applicable across different populations (e.g., European, Asian, African, Indigenous).
- Prescribing recommendations should be supported by an evidence-based guideline (e.g., CPIC, DPWG, FDA, Health Canada). Acting on prescribing recommendations that have not undergone a rigorous review process, such as that used by guideline developers, increases the risk of unexpected and potentially harmful outcomes.
Are prescribing recommendations medication-specific?
Recommendations are made at the level of each gene – medication pair. Two medications in the same class will not necessarily have equivalent recommendations. The reason is typically due to differences in how the medications are metabolized. Also, other factors (e.g., other medicines, pregnancy, cigarette use) can influence the interpretation of PGx-based recommendations for an individual.
In addition to mental health, Pillcheck covers drugs for cardiac care, gastrointestinal problems, pain management, oncology, and others. All covered treatment areas are included with every Pillcheck Report.
Results from an independent Randomized Controlled Trial (RCT) using Pillcheck confirmed the impact of this specific approach to tailoring drug treatments for people struggling with depression and anxiety.
- Practical strategies and accessible resources are available to assist physicians in effectively considering, interpreting, and implementing PGx test results. The Pillcheck service includes DNA analysis and a medication review by an expert pharmacist trained in pharmacogenomics.
- In combination with existing strategies for prescribing, PGx testing can serve as an informative complement to the psychiatrist’s toolbox.
- To reduce potential liability, physicians should become familiar with the guidelines and product labels, particularly those relevant to medications they most frequently prescribe and consider PGx test results when available.
- Using PGx facilitates shared decision-making with patients, including setting realistic expectations about how the results can be reasonably used.
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