Abstract Body: Introduction: Successful clinical trials demonstrate that new treatments are safe and efficacious. Adequate representation of underrepresented groups within clinical trials is important to build trust in research institutions and promote fairness in research. We sought to investigate whether participants in recently completed NIH StrokeNet trials were representative by race and sex compared to the expected trial population estimated from a population-based stroke study.

Methods: Since 2014, in collaboration with NIH StrokeNet, we have prepared feasibility analyses for proposed clinical trials. Thus far, 3 trials have been completed: ARCADIA, DEFUSE 3, and MOST. Our analyses used data from the 2010 epoch of the Greater-Cincinnati/Northern Kentucky Stroke Study (GCNKSS). DEFUSE 3 and MOST investigated acute treatments for ischemic stroke while ARCADIA investigated secondary stroke prevention therapies. Each study's inclusion and exclusion criteria were applied to the GCNKSS population and a percentage of eligible patients was generated. Retrospectively, we calculated the proportion of those eligible patients by race and sex and compared that to the observed proportion from each trial using Chi-square test.

Results: In 2010, there were 2265 ischemic strokes, of which 248, 74, and 135 were predicted to be eligible for ARCADIA, DEFUSE 3, and MOST, respectively. The application of the I/E criteria for each trial was limited by data available in GCNKSS, and all proposed exclusions were not able to be accounted for (namely, imaging data for DEFUSE 3 and EKG/TTE findings for ARCADIA). All 3 trials enrolled an expected number of females but DEFUSE 3 enrolled less Black participants than would have been expected (O:E ratio 0.3, p-value <0.01). Full results are available in Table 1 and Figure 1.

Conclusion: We found no statistically significant difference between the proportion of patients predicted to be eligible stratified by race and sex and the actual proportions of those enrolled for ARCADIA and MOST. For DEFUSE 3, the observed enrollment for black participants was lower than expected. All three trials enrolled near or greater than 50% females. Importantly, site selection may impact a trial’s ability to enroll different minority populations and certain clinical trial exclusion criteria may also asymmetrically affect Black patients and women. These findings should reassure that StrokeNet trials enroll a diverse population.