EVALUATING THE EFFECTS OF THE AFFORDABLE CARE ACT ON HEALTH CARE COVERAGE, UTILIZATION, AND OUTCOMES: A COMPARISON OF FOREIGN-BORN AND US-BORN POPULATIONS

Abstract

This dissertation examines the effects of the Affordable Care Act (ACA) Medicaid expansion on insurance coverage, healthcare utilization, and health outcomes among lowincome adults in the United States, with a particular focus on disparities between U.S.- born and foreign-born populations. Using nationally representative survey data and quasiexperimental methods, the three studies presented here trace the pathway from coverage gains to health system engagement and outcomes. The first paper uses American Community Survey data (2011–2019) and a differencein-differences framework with staggered adoption to estimate the impact of Medicaid expansion on insurance coverage. Results show substantial increases in Medicaid enrollment and reductions in uninsurance for both U.S.-born and foreign-born adults, though the latter experienced smaller increases in Medicaid enrollment and larger residual uninsured gaps. Notably, gains were more limited among non-citizen foreign-born adults due to legal status, policy exclusions, administrative barriers, and fear. The second paper evaluates whether coverage improvements translated into increased preventive care by analyzing colorectal and breast cancer screening rates using the Medical Expenditure Panel Survey (MEPS, 2011–2016). Findings indicate that while screening rates improved modestly for U.S.-born adults, foreign-born adults experienced smaller, non-significant gains mirroring the gap in insurance coverage. The third paper investigates the impact of the ACA Medicaid expansion on health outcomes and healthcare expenditures among low-income adults, with a focus on differences by nativity and chronic condition status using MEPS data from 2011 to 2019. This study applies a difference-in-differences framework with interaction terms to estimate changes in health-related quality of life (HRQoL), healthcare utilization (emergency department and hospitalization), and sector-specific spending. The analysis finds that while the expansion significantly reduced out-of-pocket costs and increased Medicaid-financed care—especially emergency services—it did not yield consistent improvements in healthrelated quality of life or reduce hospitalizations overall. An initial decline in mental health scores among foreign-born adults was not robust to sensitivity checks and is interpreted cautiously. Among adults with chronic conditions, avoidable emergency visits declined similarly in both groups, suggesting improvements in care efficiency and financial protection. Together, these studies underscore the complex interaction between immigration status, healthcare policy, and health equity. By applying advanced econometric methods and an intersectional lens, this dissertation highlights both the potential and the limitations of Medicaid expansion in reducing health disparities for immigrant communities. Policy recommendations include improving data collection on immigration status, addressing structural barriers to care, and ensuring inclusive access to public insurance programs.