Comparing Self-Referred and Systematically Recruited Participants in Genetic Susceptibility Testing Research: Implications for Uptake and Responses to Results.

Abstract

Studies examining whether genetic susceptibility testing for common, complex diseases can motivate individuals to improve health behaviors and advance planning have shown mixed results. An understudied area that may help reconcile these differential findings involves how testing was initiated. The overall goal of this dissertation was to understand the implications of different sampling strategies by examining self-referred versus systematically recruited populations in genetic susceptibility testing research. Using data from the Risk Evaluation and Education for Alzheimer’s Disease (REVEAL) Study, a series of randomized controlled trials exploring genetic susceptibility testing for Alzheimer’s disease (AD), I compared self-referred and systematically recruited participants in a series of secondary analyses organized into three papers. Paper 1 compared the profiles of self-referred and systematically recruited participants at enrollment, finding demographic differences (e.g., fewer African Americans and greater household incomes in the self-referred cohort), and greater AD worry among self-referred participants. Cohorts did not differ on beliefs about the benefits, risks and limitations of testing, perceptions about susceptibility, severity, causes, or controllability of AD, or self-efficacy about coping, however. Paper 2 examined responses to pretest education, finding self-referred participants more likely to learn that testing was not deterministic. Analyses of test uptake found self-referred participants more likely to retain through the initial steps of the study, but no cohort differences beyond the education phase. Paper 3 examined changes to advance planning and health behaviors after testing, finding that self-referred participants with higher-risk results were more likely than their systematically recruited counterparts to report or plan changes to long-term care insurance, mental activities, diet and exercise. Self-referred participants at increased risk also reported greater uncertainty about testing results. The two groups did not differ in post-test reports of distress or positive experiences, however, or on changes to perceptions of AD susceptibility and concern. Findings suggest that individuals proactively seeking genetic susceptibility testing for common, complex diseases are more likely to follow through with testing and use it to inform behavior changes than those who are approached by others. These results highlight the challenge of generalizing findings derived from research on self-referred populations to the population at-large.