Effect of pharmacogenomic testing on pharmacotherapy decision making in patients with symptoms of depression in an interprofessional primary care clinic.

Background: Variability in individual drug response may delay time to relief of symptoms for various disease states. As pharmacogenomic (PGx) testing becomes more widespread, providers are tasked with determining when and in who PGx testing is most appropriate. The use of PGx testing in patients with depressive symptoms has shown some utility, but how this translates to a general population within a primary care setting has yet to be determined.

Objective: The objective of this pilot study was to determine the effect of PGx testing on treatment decisions in patients with depressive symptoms in an interprofessional primary care setting.

Methods: This was a retrospective observational study in which patients who underwent PGx testing for psychotropic medications between April 2019 and March 2021 at a private interprofessional primary care clinic were identified. Charts were reviewed to determine whether a resultant change was made to the prescribed psychotropic medication regimen based on PGx testing results. The number of antidepressants trialed before and after testing was also reviewed. Data were analyzed using descriptive statistics and t test where appropriate.

Results: A total of 78 patients were included in the study. A total of 42 patients (53.8%) experienced a change to their antidepressant regimen after PGx testing. The most frequent change identified was the addition of another antidepressant (50%). This was followed by switching the antidepressant and then by an increase in dose of the prescribed antidepressant. No difference between the number of antidepressants trialed before and after testing was identified.

Conclusion: PGx testing in an interprofessional primary care setting leads to a medication change in most patients in this study. Based on the changes identified, testing may be most useful in those beginning treatment with an antidepressant or in those who experience an inadequate response to their prescribed regimen.