by A.L. Del Tredici and K.D. Becker
Recently, researchers at the Scripps Translational Science Institute and associated institutions reported on a study assessing consumer reactions to genome-wide profiling for risk of common diseases (1). Over 2,000 participants purchased the Navigenics Health Compass test at a reduced rate, and were assessed at the time of the test and three months later for anxiety, as well as changes to diet, exercise and medical screening behaviors.
The Scripps study had several notable results:
First, the major finding suggested that most – 90.3% – of the study participants did not experience any short-term increase in anxiety.
This is not a surprise, since it is consistent with other studies on physician-ordered genetic tests, showing that negative psychological impact does not occur after genetic test results were reported to the patient (2, 3). In particular, the Risk Evaluation and Education for Alzheimer’s Disease (REVEAL) Study Group showed that disclosure of genetic testing results for Alzheimer’s disease, a disease which is not preventable, did not lead to anxiety, depression or test-related distress at six weeks, six months and 12 months after test results were reported.
Secondly, while the overall study population did not show significant behavioral changes in response to the genetic information, a subset (26.5%) of the people shared their genetic report with their physician and a significant proportion of this group did make positive behavioral changes.
Study participants who discussed their test results with a physician were significantly more likely to report lowered dietary fat intake as well as increased exercise activity. Similarly, the REVEAL Study Group showed that patients with the high-risk genotype for Alzheimer’s disease were also more likely to report positive changes in health behaviors, such as diet, exercise, and vitamin use as compared to people with the non-risk genotypes (4-6). In the REVEAL study, each subject participated in a 90 minute group session led by a genetic counselor, who described the test and its limitations, discussed that behavioral changes have not been shown to prevent the disease, and provided a list of unproven behavioral changes (such as diet, exercise) which were being investigated for preventive effects.
Taken together, these data are consistent with the idea that genetic testing, when administered with a healthcare provider such as a physician or genetic counselor, can motivate patients to make positive lifestyle changes.
Lastly, the Scripps study suggests that personal genetic testing may motivate people to complete the recommended course of medical screening.
Participants found to have higher genetic risk for certain diseases (among them, colorectal cancer, type 2 diabetes, prostate cancer) were more likely to say they intended to undergo more screening for a disease. While actual completion of screening tests did not increase at three months after receiving the results, the intent to screen is the relevant factor. Completion of most screening tests requires physician authorization suggesting that personal genetic testing may increase physician-patient discussions about all the risk factors relevant to a disease or condition, not just the genetics. Further, physicians might not order additional screening above the recommended levels. An increased intent to screen by the patient leading to increased compliance would be especially beneficial with regard to screening tests with historically low compliance rates, such as colonoscopy screening for colorectal cancer (8,9). It will be interesting to see the 12-month follow-up results planned for the Scripps study.
It should be noted that the Scripps study was conducted on a sample of convenience that represents the current population of consumers that are likely to purchase personal genomic tests (1). As such, these individuals appear to be healthier prior to taking the test as compared to the broader population. It would be interesting to see if genetic testing could motivate change in a population with more typical diet and exercise levels prior to testing. Test-induced changes in dietary fat intake or exercise behavior may be more detectable in a study population that has average-to-poor diet or exercise habits at baseline, and thus, has more room for improvement.
It is encouraging to see further evidence that genetic testing does not cause psychological harm, suggesting that people can comprehend the risk factor information they learn from genetic testing without making irrational or ill-informed choices. Indeed, recent studies show that people want access to their own genetic information (7). A Tufts University study indicates that a majority (~80%) of Americans would be willing to pay for a genetic test, even if the test is ‘not perfectly accurate and even if the test could only disclose a small proportion of the risk of developing a disease’ (10).
The Scripps study focused on the potential of personal genetic testing to motivate patients to make healthful lifestyle changes. Of course, genetic tests are already used by physicians to improve medical care. Carrier testing, for example, has been used by physicians for decades to help patients make reproductive decisions. Many physicians are also using pharmacogenetic testing to choose the most effective medicines for their patients. Genetic testing for common diseases, such as the tests surveyed in the Scripps study, may be helpful to identify individuals at high risk of developing prostate cancer or other diseases, who may benefit from more invasive and sensitive screening tests (11, 12).
The Scripps study results support the view that healthcare provider involvement in the genetic testing process will give patients the greatest opportunity to improve their health. The real benefit may be derived from patients engaging their healthcare providers in a detailed discussion of their health before they are ill. Healthcare providers can use genetic tests as supplemental information combined with their knowledge of all the factors that relate to the risk of any particular disease for their patients. Provided with this knowledge, the Scripps study suggests that some patients will make the behavioral changes necessary to improve their health.
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