Pharmacogenomic Testing for Psychotropic Medication Selection: A Systematic Review of the Assurex GeneSight...

A large proportion of the Ontario population lives with a diagnosed mental illness. Nearly 5% of Ontarians have major depressive disorder, and another 5% have another type of depressive disorder, bipolar disorder, schizophrenia, anxiety, or some other disorder not otherwise specified. Medications are commonly used to treat mental illness, but choosing the right medication for each patient is challenging, and more than 40% of patients discontinue their medication within 90 days because of adverse effects or lack of response. The Assurex GeneSight Psychotropic test is a pharmacogenomic panel that provides clinicians with a report to guide medication selection that is unique to each patient based on their individual genetic profile. However, it is uncertain whether guided treatment using GeneSight is effective compared with unguided treatment (usual care).

We performed a systematic review to identify English-language studies published before February 22, 2016, that compared GeneSight-guided care and usual care among people with mood disorders, anxiety, or schizophrenia. Primary outcomes of interest were prevention of suicide, remission of depression symptoms, response to depression therapy, depression score, and quality of life. Secondary outcomes of interest were impact on therapeutic decisions and patient and clinician satisfaction. Risk of bias was evaluated, and the quality of the evidence was assessed using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) working group criteria.

Four studies met the inclusion criteria. These studies used a version of GeneSight that included the CYP2D6, CYP2C19, CYP1A2, SLC6A4, and HTR2A genes; one of the studies also included CYP2C9. Patients who received the GeneSight test to guide psychotropic medication selection had improved response to depression treatment, greater improvements in measures of depression, and greater patient and clinician satisfaction compared with patients who received treatment as usual. We observed no differences in rates of complete remission from depression. The findings were based on GRADE assessment of low to very low quality evidence, and the body of evidence had several limitations: the included studies used an older version of GeneSight and were limited to a population with major depression, so results may not be generalizable to other versions of the test or different populations such as patients with anxiety or schizophrenia.

There is uncertainty about the use of GeneSight Psychotropic pharmacogenomic genetic panel to guide medication selection. It was associated with improvements in some patient outcomes, but not others. As well, our confidence in these findings is low because of limitations in the body of evidence.