Impact of Previous Genetic Counseling and Objective Numeracy on Accurate Interpretation of a Pharmacogenetics Test...

Pharmacogenetic (PGx) testing can be useful for providing information about a patient's drug response by increasing drug efficacy and decreasing the incidence of adverse drug events. While PGx tests were previously only offered to patients under healthcare provider supervision, they are now available as direct to consumer (DTC) tests. This study aimed to assess how accurately individuals from the general population were able to interpret a sample PGx test report and if accuracy differed based on individuals' numeracy or prior genetic counseling (GC).

We surveyed 293 individuals from the general population, ascertained through ResearchMatch. The survey included questions about PGx test interpretation, numeracy, and genetic literacy.

In our cohort, numeracy level impacted PGx result interpretation, with those of high numeracy performing statistically significantly better on both the table format and graphical format (p value = 0.002 and p value <0.001, respectively) and genetic knowledge questions (p value <0.001) than those with low/average numeracy. In addition, previous GC did not impact test interpretation or genetic knowledge, but the number of individuals with prior GC was small (n = 26).

We found that numeracy had a significant impact on correct interpretation of PGx test reports. Because many individuals in the USA have low numeracy levels, it is extremely important that patients do not make their own medication management decision based on the test results and that they consult with their physicians about their PGx testing. The importance of consultation and discussion with providers about results should be emphasized on the test report.