On averages and peaks: How do people integrate attitudes about multiple diseases to reach a decision about multiplex genetic testing?

Background. The aim of the current study was to learn how people integrate attitudes about multiple health conditions to make a decision about genetic testing uptake. Methods. This study recruited 294 healthy young adults from a parent research project, the Multiplex Initiative, conducted in a large health care system in Detroit, Michigan. All participants were offered a multiplex genetic test that assessed risk for 8 common health conditions (e.g., type 2 diabetes). Data were collected from a baseline survey, a web-based survey, and at the time of testing. Results. Averaging attitudes across diseases predicted test uptake but did not contribute beyond peak attitudes, the highest attitude toward testing for a single disease in the set. Peak attitudes were found sufficient to predict test uptake. Limitations. The effects of set size and mode of presentation could not be examined because these factors were constant in the multiplex test offered. Conclusions. These findings support theories suggesting that people use representative evaluations in attitude formation. The implication of these findings for further developments in genetic testing is that the communication and impact of multiplex testing may need to be considered in the light of a bias toward peak attitudes.