Are older adult research participants representative of the general population? Results from 19 clinical studies at one academic research center

BACKGROUND: To implement strategies for enhancing research participation across a broad range of personal characteristics, additional data are needed regarding the degree of underrepresentation of specific individuals in research. METHODS: This study analyzed data from 3671 older (mean age 69 yrs) individuals enrolled in 19 studies conducted from 2002 to 2023 at Wake Forest University School of Medicine. Study inclusion was limited to those with a minimum age eligibility of 50 years. Demographic data of enrolled participants were compared to 1) individuals phone screened for participation and 2) US Census data of older individuals residing in the zip codes of the catchment area. RESULTS: There were 11 studies with screening data available, and the overall enrollment yield was 11.1% (n = 2207 of n = 19,895 screened). Those enrolled were similar in age to those who screened out, and a greater proportion of males (14.5%) versus females (12.4%) and White (22.3%) versus Black participants (19.4%) were enrolled after screening. Compared to Census estimates of older adults, individuals that were 75+ years at enrollment were underrepresented (Census 29%, enrolled 18%; PPR = 0.6), older adults with at least some college education were overrepresented (Census 24%, enrolled 80%; PPR = 3.27) and individuals who specified Black or African American ethnicity were slightly overrepresented (Census 14%, enrolled 19%; PPR = 1.31). Older adults who were 65 years or older, female, or had White ethnicity had proportional representation at enrollment. CONCLUSIONS: The research participants included across these studies had underrepresentation of adults older than 75 years and overrepresentation of college-educated and Black or African American race.