Association between state Medicaid policies and accrual of Black and Hispanic patients to cancer clinical trials.
Authors: Takvorian Samuel U , Schpero William L , Blickstein Daniel , Shafquat Afrah , Liu Jingshu , Chatterjee Arnaub , Lamont Elizabeth B. , Chatterjee Paula 
Published: June 2023

1510 Background: The U.S. Medicaid health insurance program may play a key role in mitigating racial and ethnic disparities in cancer clinical trial enrollment, given Medicaid’s disproportionate representation of these populations and its coverage of the routine costs of trial participation in some states. We sought to evaluate the effect of Medicaid expansion under the Affordable Care Act (ACA) on changes in the accrual of racial and ethnic minority patients in cancer clinical trials, across all states and specifically those mandating Medicaid coverage of routine trial costs. Methods: The study used anonymous enrollment data from Medidata Rave, a large commercial clinical trial data collection platform. We conducted a retrospective difference-in-differences (DID) analysis to examine accrual demographics in states that expanded Medicaid eligibility under the ACA compared with non-expansion states, before and after expansion; and assessed effect modification based on state-mandated Medicaid coverage of routine trial costs. Participants included adults enrolled in interventional cancer clinical trials from 2012-2019, located in U.S. hospital referral regions with >5% Black or Hispanic population. The primary outcome was participant race/ethnicity, defined dichotomously as Black or Hispanic (vs non-Black, non-Hispanic). We used ordinary least squares regression to model participant race/ethnicity as a function of (1) an indicator for trial enrollment in an expansion state after policy implementation, (2) state fixed effects, and (3) year fixed effects, with standard errors clustered at the state level. To assess effect modification, we stratified the main model across states with and without coverage mandates of routine trial costs. Results: The study included 75,700 participants across 1,409 clinical trials and 351 sites. In expansion states, the proportion of participants who identified as Black and/or Hispanic increased from 13.4% before expansion to 13.8% after expansion (0.4 percentage-point [PP] change, 95% CI -0.8 to 1.7). In non-expansion states, this proportion decreased from 17.0% to 15.2% (-1.7 PP change, 95% CI -3.7 to 0.2). These trends yielded a non-significant DID estimate of 2.0 PP (95% CI -1.0 to 5.0). In stratified analyses, Medicaid expansion was associated with a 4.5 PP (95% CI 0.4 to 8.6) increase in the enrollment of Black and/or Hispanic participants in states with coverage mandates, but not in states without coverage mandates (1.1 PP, 95% CI -2.6 to 4.8). Conclusions: Medicaid expansion was associated with a significant increase in the proportion of Black and Hispanic oncology trial participants in states that mandated Medicaid coverage of the routine costs of trial participation, but not overall across all states. These findings suggest that Medicaid policies have the potential to advance equitable enrollment in cancer clinical trials.