Comparison of sample characteristics of Wisconsin Alzheimer's Disease Research Center participants with the Wisconsin state population-An evaluation of the recruitment effort

Introduction: Understanding how a research sample compares to the population from which it is drawn can help inform future recruitment planning. We compared the Wisconsin Alzheimer's Disease Research Center (WADRC) participant sample to the Wisconsin state population (WI-pop) on key demographic, social exposome, and vascular risk measures.

Methods: The WADRC sample included 930 participants. Population statistics were estimated using several national and state data sources. We compared WADRC to WI-pop for two age groups, 45-64 years and ≥65 years, separately.

Results: Compared to WI-pop, WADRC participants were older and included more women, more Black and American Indian individuals, and fewer Hispanic and Asian individuals. WADRC participants had higher levels of educational attainment, consisted of smaller proportions living in rural areas and disadvantaged neighborhoods, and showed lower vascular risks. Greater differences between WADRC and WI-pop were found for most metrics in the ≥65 group compared to the 45-64 group.

Discussion: The findings revealed opportunities to increase enrollment from the Hispanic/Latino and Asian American populations, to include participants from a broader range of educational backgrounds, and to enroll more residents from rural areas and disadvantaged neighborhoods, which may lead to a broader distribution of cardiovascular risk factors. Expanding sociodemographic and health profiles represented in the participant candidate pool for study selection and including those who are underrepresented in research may potentially reduce selection bias but not eliminate it. Statistical approaches can be applied to address bias and generalize findings from a study sample to its target population by adjusting for their differences in the joint distribution of covariates. Although research centers have different regional populations and specific recruitment focuses for scientific reasons, evaluating their participant characteristics may help plan engagement efforts to improve the inclusion of underrepresented groups and collaboratively support generalizable research nationwide.

Highlights: We compared the characteristics of Wisconsin Alzheimer's Disease Research Center (WADRC) participants with the Wisconsin population.Metrics of comparison included demographics, social exposomes, and vascular risks.WADRC participants are different from the Wisconsin population.We explored the implications and causes of the differences.We discussed strategies for engaging and recruiting underrepresented groups.