Abstract
PURPOSE: It is unknown whether Medicaid expansion under the Affordable Care Act (ACA) or state-level policies mandating Medicaid coverage of the routine costs of clinical trial participation have ameliorated longstanding racial and ethnic disparities in cancer clinical trial enrollment. METHODS: We conducted a retrospective, cross-sectional difference-in-differences analysis examining the effect of Medicaid expansion on rates of enrollment for Black or Hispanic nonelderly adults in nonobservational, US cancer clinical trials using data from Medidata's Rave platform for 2012-2019. We examined heterogeneity in this effect on the basis of whether states had pre-existing mandates requiring Medicaid coverage of the routine costs of clinical trial participation. RESULTS: The study included 47,870 participants across 1,353 clinical trials and 344 clinical trial sites. In expansion states, the proportion of participants who were Black or Hispanic increased from 16.7% before expansion to 17.2% after Medicaid expansion (0.5 percentage point [PP] change [95% CI, -1.1 to 2.0]). In nonexpansion states, this proportion increased from 19.8% before 2014 (when the first states expanded eligibility under the ACA) to 20.4% after 2014 (0.6 PP change [95% CI, -2.3 to 3.5]). These trends yielded a nonsignificant difference-in-differences estimate of 0.9 PP (95% CI, -2.6 to 4.4). Medicaid expansion was associated with a 5.3 PP (95% CI, 1.9 to 8.7) increase in the enrollment of Black or Hispanic participants in states with mandates requiring Medicaid coverage of the routine costs of trial participation, but not in states without mandates (-0.3 PP [95% CI, -4.5 to 3.9]). CONCLUSION: Medicaid expansion was not associated with a significant increase in the proportion of Black or Hispanic oncology trial participants overall, but was associated with an increase specifically in states that mandated Medicaid coverage of the routine costs of trial participation.