The Option of Genetic Testing
Table 1. Clinical Utility of Genetic/Genomic Testsa continued...
DTC laboratories predominantly rely on Web material to disseminate test information to consumers. One study evaluated how using a Web-based decision tool that provided information about a multiplex genetic susceptibility test influenced participants' testing decisions. The Web-based tool was developed specifically for the study by an interdisciplinary research team and was designed using principles of health literacy, communication, and prior research. The tool implemented a layered menu approach that allowed participants to select the order and amount of content viewed. Participants included 526 members of a large Midwestern health maintenance organization ranging in age from 25 to 40 years with no evidence of any of the health conditions included in the test. Participants most frequently viewed the Web pages describing the test, testing procedures, and implications of the results and less frequently viewed the pages about specific health conditions or genes. Participants viewed an average of eight Web pages (mean 8.2, standard deviation 7.2, range 1–27), including an average of 2.9 of the 4 pages introducing the multiplex test, 2.2 of the 8 pages describing the health conditions on the test, and 3.2 of the 15 pages describing the genes, out of a possible 27 total pages. The number of Web pages viewed was significantly associated with ease of decision making (odds ratio, 1.04; 95% CI, 1.01–1.07).
There is growing interest in trying to use genetic information to guide decisions about healthy lifestyle, including dietary choice, although there is no evidence base for implementing such practices. A 2006 study of consumer and physician awareness of DTC nutrigenomic tests found that 14% of consumers and 44% of physicians had heard of the tests, but actual utilization was exceedingly low (0.6% of consumers had used one). This study examines awareness of nutrigenomic testing in Michigan, Oregon, and Utah via the 2006 Behavioral Risk Factors Surveillance System. Awareness was highest in Oregon (24.4%) and Utah (19.7%) and lowest in Michigan (7.6%). Those who had higher incomes, greater education, and increasing age (except those older than 65 years) were more aware of nutrigenomic tests. Of those consumers who had heard of DTC nutrigenomic tests, 46% had heard about them from television, 35% from magazines, 29% from newspapers, and only 13% from health professionals. There was great variation in the extent to which background information concerning the disease in question was presented. For example, more than half of these companies offered information about disease etiology, but far fewer offered information about diagnosis and treatment or prevention. Companies providing tests of little clinical utility (such as enhancement tests) tended to provide more detailed information, although the information provided about the diseases and genetics in general was not always accurate, as clinical validity claims were supported by peer-reviewed literature in only approximately half the companies. The trend identified in this survey of available companies indicates that the tests with the least clinical utility are provided with the least professional oversight and counseling services.