The purpose of this study was to investigate study participant representativeness within intramural clinical protocols, with an initial focus on epilepsy, to assess equitable selection of subjects.
A retrospective assessment of all intramural clinical studies from January 2005 to December 2022 was performed. Demographic data included race, ethnicity, zip-code, and home state was compared to CDC, US Census Bureau, and published literature estimates.
20797 participants across 331 protocols from 2005-2022, including 739 participants in four epilepsy protocols were analyzed (2008-2022). Compared to Census (2008-2021), overall White enrollment was lower (73.3% vs 77%) and Black enrollment was only slightly lower (13.1% vs 13.26%). Total Hispanic/Latino recruitment was lower (7.9%), compared to Census (17.4%). However, the epilepsy protocol recruitment compared to 2013-2015 CDC epilepsy data demonstrated higher Black Non-Hispanic cohort enrollment (29% vs 18%), and lower rate of White Non-Hispanic enrollment (56% vs 66%). Epilepsy participants on average for DC-specific enrollment were more likely to be Black Non-Hispanic (47% vs 31%) and less likely to be White Non-Hispanic (42% vs 53%). Rates of Hispanic/Latino were similar (5% epilepsy vs 4% overall; p=0.02 for overall proportions). Published estimates demonstrate significantly higher Black Non-Hispanic epilepsy prevalence in DC than is captured by cohort (74%; p=0.001).
Overall, demographic enrollment demonstrated lower White Non-Hispanic, higher Black Non-Hispanic, and comparable other racial groups compared to Census data. The largest disparity was a 9.5% difference in Hispanic/Latino enrollment, indicating a potential recruitment target. The epilepsy cohort revealed that while rates of Hispanic/Latino were comparable to the local DC population, there were significantly fewer Black Non-Hispanic subjects enrolled than expected, although the overall trend was a higher Black Non-Hispanic enrollment.