Leighton: Public May Misinterpret Genetic Test Results for Cancer, Heart Disease

By Purnell T. Cropper | October 22, 2010

“Direct-to-consumer (DTC) genetic testing allows consumers to discover their risk for developing common complex disorders without involving a medical professional. Consumers may not understand test results, leading to negative consequences including unnecessary concern, false reassurance, or unwarranted changes in screening behaviors,” according to a poster presentation by Justin Leighton, Arcadia University Genetic Counseling student, at the National Society of Genetic Counselors (NSGC). The General Public’s Understanding and Perception of Direct-to-Consumer Genetic Test Results was authored by J. Leighton1, B. Bernhardt2, K. Valverde1. (1Arcadia University, 2University of Pennsylvania).

“To investigate consumers’ perceptions and understanding of DTC test results, an online survey was posted on facebook.com that included questions relating to four sample test results for risk of developing colorectal cancer, heart disease, and skin cancer. Genetic counselors (GCs) were used as a comparison group and completed the same survey through the National Society of Genetic Counselors’ listserv. 145 individuals from the general public (GP) and 171 GCs completed the survey.

“A significant difference (p<.05) was found between the GP and GCs understanding of genetic test results in three of four scenarios. When results were presented in terms of relative risks, GP respondents were significantly more likely to misinterpret risks than were GCs. When presented with a scenario providing results indicating a slight reduction in absolute risk, GP respondents were significantly more likely to believe their risk was ‘much lower.’ With respect to medical management, the GP thought results in all four scenarios would be significantly more helpful than did GCs.

“Although the majority of GP respondents rated the results either very easy or easy to understand, they often were unable to correctly interpret the results. For example, in the scenario involving a relative risk of 1.45 for developing colon cancer, 71 of the GP respondents felt that results were easy to understand, but only 42 (59%) of them correctly interpreted the results.

“These findings imply that the GP has the potential to misinterpret DTC results without appropriate assistance. Further research is needed exploring optimal methods of providing DTC test results and ways to minimize the risk of negative consequences for consumers.”