Racial, ethnic disparities occur in recruitment for preclinical Alzheimer’s disease trial

Differences in sources of recruitment, reasons for screen failure and overall probability of eligibility occurred across racial/ethnic groups included in a large preclinical Alzheimer’s disease trial conducted in North America.

Researchers published results on the racial and ethnic differences observed in the trial in JAMA Network Open.

“Preclinical AD trials face difficulty in recruiting diverse participants, perhaps in part due to unique challenges in these novel studies,” Rema Raman, PhD, professor of neurology at the University of Southern California’s Keck School of Medicine and director of biostatistics at the USC Alzheimer’s Therapeutic Research Institute, University of Southern California, and colleagues wrote. “We examined the sources of recruitment and the reasons for screen failure among underrepresented racial and ethnic group participants in the first preclinical AD trial, the Anti-Amyloid treatment in Asymptomatic Alzheimer (A4) study.”

Raman and colleagues performed a cross-sectional study using data from the A4 study, collected from April 2014 to December 2017. The researchers grouped participants into five mutually exclusive, self-reported ethnic/racial groups that included Hispanic, Black, white, Asian and other. Raman and colleagues assessed the data from 5,945 cognitively unimpaired older adults aged 65 to 85 years screened at North American study sites from May through December 2020.

Recruitment sources, study eligibility and ineligibility reasons served as the study’s primary outcomes. The researchers conducted regression analyses for the likelihood of being eligible after the first screening visit involving clinical and cognitive assessments to evaluate the probability of trial eligibility.

The study included more women (59.3% of the total study population) and the mean age of participants was 71.7 years. Most participants (n = 5,107) were white; 323 were Black, 261 were Hispanic, 112 were Asian and 142 reported race/ethnicity as other, according to the study results.

Raman and colleagues noted recruitment sources were different based on race or ethnicity. Although white patients were recruited through multiple sources, site local recruitment efforts were observed in the majority of Black (218 [69.2%]), Hispanic (154[59.7%]), and Asian (61 [55.5%]) patients enrolled.

“Participants from underrepresented groups had lower mean years of education (eg, mean [SD] years: Hispanic participants, 15.5 [3.2] years vs. white participants, 16.7 [2.8] years) and more frequently were women (226 [70%] Black participants vs. 1,364 [58.5%] white participants), were unmarried (184 [56.9%] Black participants vs. 1,364 [26.7%] white participants), and had nonspousal study partners (237 [73.4%] Black participants vs. 2,147 [42%] white participants),” Raman and colleagues wrote.

The researchers found that patients from underrepresented groups were excluded more often due to failure to meet cognitive inclusion criteria (147 Black patients [45.5%] vs. 1,338 white patients [26.2%]). Black patients (OR, 0.43; 95% CI, 0.34-0.54), Hispanic patients (OR, 0.53; 95% CI, 0.41-0.69) and Asian patients (OR, 0.56; 95% CI, 0.38-0.82) were less likely to be eligible after screening visit 1 compared with white patients, according to the study results.

“These findings suggest that there are racial and ethnic disparities in preclinical AD clinical trial enrollment that will require a comprehensive approach to study design and recruitment strategies to minimize disproportionate enrollment,” Raman and colleagues wrote.

In a related editorial, Jennifer J. Manly, PhD, of the Taub Institute for Research on Alzheimer’s Disease and the Aging Brain in the department of neurology at Columbia University Irving Medical Center, New York, Andrea Gilmore-Bykovskyi, PhD, RN, of the School of Nursing at the University of Wisconsin–Madison, and Kacie D. Deters, PhD, of the department of neuroscience at the University of California San Diego, wrote that the results from Ramon and colleagues and the A4 trial demonstrate the need “to consider the lasting implications of engaging underrepresented communities to recruit for a research trial and then deeming most willing people ineligible.”

Manly, Gilmore-Bykovskyi and Deters noted Raman and colleagues found prospective patients who were “white, well-educated and well-resourced” were the focus at each step of the trial’s design, which they also acknowledged in the study results.

“These conventional research recruitment practices and deeply entrenched norms were associated with the recruitment of participants from minoritized backgrounds,” Manly, Gilmore-Bykovskyi and Deters, wrote. “It is a worthy exercise to question the ways these practices do and do not facilitate participation in some groups, but the field can also benefit from reflecting on why the systems and structures of recruitment are so commonly designed around white, resourced populations as a prioritized, referent norm. An example of this ethnocentric approach is seen in the discussion about racial/ethnic differences in the availability and relationship of study partners in the A4 study; namely, more Black and Hispanic people were excluded because they did not have a study partner with whom they had weekly contact.”