As PGx testing expands across medical specialties and into primary care, a larger proportion of the public will begin to encounter these tests. In addition to demonstrating the clinical utility and ensuring coverage of testing, the translation of PGx tests will be influenced by patient attitudes and interest. Past surveys have reported favorable support for PGx testing and our findings are consistent with these results in a national U.S. sample.
Level of interest in PGx testing is comparable to the generally high interest reported for genetic testing for colon cancer5
or hereditary cancers in general4, 6–8
and heart disease.6, 8, 9
There are conflicting data on the relationship between level of education and attitudes toward genetic testing.9, 27–30
Some studies have found an inverse relationship between education level and positive attitudes toward genetic testing.9, 28
Others have found that individuals knowledgeable about genetic testing have more positive attitudes towards testing29
but also may express skepticism.27
Yet other surveys find no evidence to support a correlation between knowledge about biotechnology in general and attitudes towards it.31
Although 20% of respondents in our survey had not heard of genetic testing, we did not observe a relationship between overall interest in PGx testing and awareness. However, we found that those with less than a college degree had a lower interest in PGx testing after being informed of the risks; this association disappeared after they learned about the specific uses of testing. Similar to other studies,32
we found greater awareness of genetic testing in Whites compared to non-Whites, but race was not associated with overall interest in PGx testing.
The order of information presented about genetic testing can affect attitudes toward testing with the information presented first being more influential.24
After assessing overall interest, we did not find presentation of the risks first as most influential, perhaps due to high general interest in genetic testing or familiarity and/or experience with drug side effects or non-response. However, when presented with individual risks such as loss of confidentiality, only a minority indicated they would be interested in PGx testing. Despite the nearly 10-year gap between the two surveys, our findings were comparable to Rothstein & Hornung (2003) with respect to interest in PGx testing given concerns about confidentiality (78% in our survey vs. 70% in their survey would be less likely to undergo PGx testing). As we did not disclose the fact that federal law now prohibits discriminatory actions by health insurers or employers (regulations were still pending at the time the survey was administered), it is not certain whether knowledge of federal protections would have increased interest following presentation of individual risks. Given ongoing concerns, disclosure of these policies should be a required element of the discussion about PGx testing with patients.
As anticipated, presentation of the different uses of PGx testing boosted interest. We had hypothesized that the public would vary in their level of interest of different uses of a PGx test as some uses may be considered more important than others, but found little difference. Commonalities existed between factors predictive of interest in PGx testing given certain risks or intended uses, though no single characteristic was predictive of likelihood, suggesting that a combination of personal factors, awareness of genetics, and health and medication history influence interest in PGx testing. The absence of significant differences could also be attributed to lack of understanding of the different specific test uses (e.g., effectiveness vs. safety). The lack of context or details of a specific treatment scenario may have also resulted in generally high interest in all uses. Four factors were significantly associated with interest in testing for two of the three risks and intended uses presented: awareness of genetic testing, race, education, and personal history of side effects. The lower interest in PGx testing by non-Whites given some risks and intended uses may indicate differences in perceived harms (higher) and value of the information (lower), potentially attributed to mistrust of genetic testing33, 34
or the health system in general, but not strong enough to influence overall interest in testing. Interestingly though, race and education were not associated with likelihood of testing given risk of loss of confidentiality as reported by Rothstein & Hornung (2003). Our finding that history of side effects was linked to overall interest confirm previous findings with respect to PGx testing,17, 35
analogous to the higher interest in genetic testing in at-risk individuals (i.e., those with a family history).36, 37
Of the minority of respondents that indicated they were initially not very or not at all likely to have a PGx test, about half indicated they would be interested in a non-genetic test that provided similar information about drug response, suggesting that development of non-DNA-based PGx tests may help increase uptake. Interest in a non-genetic test was associated with higher education status, possibly suggesting greater awareness of potential risks of testing. Shields et al.38, 39
reported that primary care physicians would be more likely to order a non-genetic test compared to a genetic test to predict response to smoking cessation therapy, suggesting some reluctance, either on the part of physicians or their belief that their patients would be reluctant to consent to a genetic test. Of our respondents who were unlikely to have any testing for drug response, genetic or otherwise, we speculate that other concerns not related to ‘genetic testing’ account for their lack of interest in testing. Given the long-term benefits of PGx testing over a patient’s lifetime, declining testing could have multiple adverse consequences including access to best available therapies if testing is required prior to use. Thus, careful consideration must be given to weighing the benefits and risks of use of a given treatment if testing is not performed, coverage policies of treatments without testing, and alternative approaches to monitoring adverse responses.
Given the sometimes different allele prevalence between populations, it will be essential to include as diverse study populations as possible to ascertain PGx associations as well as potential physiologic functional differences. Groups with lower interest in PGx testing may be less inclined to participate in such studies, creating a significant knowledge gap. On the other hand, groups with higher interest in PGx testing, such as individuals with prior experience of side effects, may be more interested in participating in PGx research. Careful attention should be given to assessing outcomes based on patient self-reporting to minimize confounding.
As the clinical evidence basis increases and PGx testing is routinely ordered in the clinic, it is critical to ascertain the public’s interest and perceived barriers to this new application. The public is strongly supportive of PGx testing, however, their interest is influenced by a combination of factors, most notably prior experience with side effects. Although informed consent is not usually obtained for PGx tests currently40–42
given the different levels of interest among some groups, providers should discuss the exact purpose of testing, alterative testing options (if available), and the protections in place to protect their privacy and confidentiality. While the high level of interest in PGx testing is encouraging, public interest in genetic testing may not translate to high uptake.43, 44
Patients recommended PGx testing in an actual clinical situation may respond differently depending on the circumstances of the situation or potential other factors not raised in this study. Thus, clinical studies will be needed to assess actual uptake of testing, with a particular focus on patients who are declining testing, such as assessing factors that impact patient decisions regarding testing such as patient expectations and/or concerns about testing . Based on these data gathered from a real-world setting, we will gain a better understanding of the barriers to actual uptake or refusal that may inform changes in the delivery of PGx testing, patient communication, and application of PGx testing to therapeutic decision-making.