Did Medicaid Reimbursements Shape the Effects of Medicaid Expansion on Access to Health Care Among the Low-Income Population?

Background: Whether variation in Medicaid reimbursement fees influenced the impacts of the Medicaid expansions is not well understood.Objective: We examine whether changes in health care access associated with Medicaid expansion are different in states with comparatively high Medicaid reimbursement rates compared against expanding in states with lower Medicaid reimbursement rates.Design: Using a difference-in-difference-in-difference (DDD or triple-difference) regression approach, we compare relative differences in Medicaid expansion effects between lower and higher reimbursement states.Participants: 512,744 low-income adults aged 20-64 in the 2011-2019 Behavioral Risk Factor Surveillance System.Main Measures: Health insurance coverage status, unmet medical needs due to cost, regular source for health care, and a regular/scheduled checkup within the past year.Key Results: Medicaid expansion has significant and positive impacts on health coverage and access in both high- and low-fee states. In states with fee levels above the median Medicare-to-Medicaid ratios, expanding Medicaid eligibility reduced uninsurance rate by 15.2 percentage point (ppt, p < 0.01), shrank the cost-associated unmet medical need by 10.3 ppt (p < 0.01), improved access to usual source of care by 1.9 ppt (p < 0.1), and increased regular checkup by 14.4 ppt (p < 0.01), while such effects in low-fee states were 11.7 ppt (p < 0.01), 8.3 ppt (p < 0.01), 3.1 ppt (p < 0.1), and 12.3 ppt (p < 0.01), respectively. Our results suggest that Medicaid expansion effect on unmet medical need due to cost in higher-reimbursing states was 2.98 ppt (p < 0.05) larger than in lower-reimbursing states. Evidence suggests modest increases in health care access were more strongly associated with expansions in higher-fee states.Conclusions: Medicaid's fee structure should be considered as a factor influencing large-scale coverage expansions.