Predictors of Clinical Trial Participation Among Older U.S. Adults With Multimorbidity: A Cross-Sectional Survey

Older adults, women, and minorities are under-represented in clinical trials. Our objective was to identify characteristics predicting participation in clinical trials of medications in a diverse sample of older adults; and, secondarily, identify current participation motivators and barriers and trial preferences. A cross-sectional U.S. community convenience sample survey of adults > 65 years with > 3 chronic medical conditions querying attitudes about participation in clinical trials was conducted from March 2023-October 2024 in English and Spanish. Formats were yes/no or three-point Likert scale answers. Multivariable logistic regression identified characteristics with higher likelihood of trial participation. Surveys were from 2176 older adults (White (50.3%), Black/African American (18.5%), Hispanic/Latino (17.7%), Asian (13.5%) aged 73.1 ± 6.1 years (mean, SD), 52% women,one 4.1 ± 1.9 medical conditions; taking 7.4 ± 3.2 medications. Characteristics with higher likelihood of trial participation were higher income (1.36, 0.93-1.99; Odds Ratio, 95% Confidence Interval), educational status (1.88, 1.12-3.0), greater health literacy (2.07, 1.29-3.3), having cancer (1.49, 1.11-1.99) or chronic pain (1.55, 1.17-2.06), Black/African American race (1.44, 1.02-2.02) or Hispanic/Latino race/ethnicity (1.55, 1.11-2.16). Females had lower likelihood of participation (0.66, 1.29-3.32) as did age 75 and above (0.67, 0.50-0.92). Disincentives in women were potential side effects, placeboes, visit travel > 1 h, and video visits. Prior participants and nonparticipants were more likely to consider participation after physician recommendation (92% and 76.4%, respectively). Better care would motivate the highest percentage of all respondents. Education about trials including possible benefits, addressing concerns of women, physician involvement during recruitment and trials with in-person visits may increase representative enrollment.