Genetic testing may benefit patients with depression

A new study by U.S. Department of Veterans Affairs found that pharmacogenomic testing can help providers avoid prescribing antidepressant medications that may have undesirable outcomes. Pharmacogenomics is the study of how genes affect the body's response to drugs.

The researchers also found that the patients who underwent genetic testing had more positive outcomes, compared with patients in usual care. Over 24 weeks of treatment, the group with genetic testing had in a drop in depression symptoms with a peak effect at 12 weeks. Each patient in the study had major depressive disorder. Symptoms of that health condition include insomnia, loss of appetite, feelings of sadness and depression, and thoughts of dying by suicide.

The results appeared in July 2022 in the Journal of the American Medical Association.

The patients enrolled in the study were initiating or switching treatment with an antidepressant drug. The study included nearly 2,000 patients from 22 VA medical centers who were randomized evenly, with half receiving pharmacogenomic testing and the other half getting usual care. Oslin and his colleagues aimed to learn if genetic testing helped patients receive fewer medications with predicted drug-gene interactions and if that produced better outcomes.

A drug-gene interaction is an association between a medication and a genetic variant that may affect a patient's response to drug treatment. Having that information helps the provider select the appropriate dosage for a specific patient.

The patients in the control group received genetic testing, but their providers didn't see the results. That meant those providers made medication choices for their patients that weren't supported by pharmacogenomic tests. The study found a marked shift in prescribing away from medications with significant drug-gene interactions or moderate drug-gene interactions.

Overall, 59% of the patients in the genetic testing group received a medication with no predicted drug-gene interaction, compared with 26% in the control group. The researchers defined that difference as "statistically significant and clinically meaningful" ended the authors.

Reference: "Effect of pharmacogenomic testing for drug-gene interactions on medication selection and remission of symptoms in major depressive disorder: the PRIME Care randomized clinical trial." Journal of the American Medical Association, DOI: 10.1001/jama.2022.