Revisiting Medicaid Expansion: Uneven Effects Across Patients, Providers, and Other Insurance Markets

Session Submission Type: Panel

Abstract

More than a decade after the Affordable Care Act established Medicaid expansion as a cornerstone of its coverage strategy, a growing body of research shows that its effects are neither uniform nor fully anticipated by program designers. This panel brings together four papers by Economists and Health Policy researchers that examine how expansion operates through behavioral responses, market segmentation, and broader economic spillovers, using a wide range of descriptive, quasi-experimental, and structural methods.

The first paper examines how the Affordable Care Act’s Medicaid expansion affected cesarean deliveries, focusing on low-risk nulliparous, term, singleton, vertex (NTSV) births and examining heterogeneity by race and ethnicity. Using the U.S. National Vital Statistics System microdata and a difference-in-differences approach, the authors find no average effect on cesarean rates but substantial heterogeneity across racial and ethnic groups. The second paper studies cancer outcomes and shows that the benefits of Medicaid expansion depend on geographic access to oncology care. While Medicaid expansion improves survival and reduces mortality on average, the authors show that gains are larger in areas with shorter travel times to providers. The last two papers of the panel study the spillover effects of Medicaid expansion on the Affordable Care Act’s Marketplace. Specifically, the third paper uses data from the Centers for Medicare & Medicaid Services Appendix A risk adjustment summaries and synthetic difference-in-differences; the authors show that Medicaid expansion re-sorts risk across insurance markets, thereby reducing the average risk profile of ACA individual market enrollees without significantly affecting premiums. The final paper develops a structural model of adjacent insurance markets to simulate the effect of adjusting the Medicaid eligibility threshold to the local cost of living. Using administrative data from California, the paper shows that adjusting eligibility thresholds increases aggregate consumer surplus net of public spending across all designs considered, but the gains vary widely across regions. The paper highlights how the design of eligibility thresholds interacts with market structure and insurer incentives in segmented health insurance markets.

Policy Area

• Health Policy

Chair

• Joseph Benitez, University of Kentucky

Discussants

• Sungjin Lee, San Diego State University

• Laura Montenovo, Purdue University

Organizer

• Salpy Kanimian, Brown University

Individual Presentations

• The Differential Impacts of Medicaid Expansion on Cesarean Births by Race and Ethnicity - Presenting Author: Hyesung Oh, California State University, Long Beach

• Heterogenous Effects of Medicaid Expansion: The Moderating Role of Geographic Access to Oncology Care - Presenting Author: Kristine Jenny Hahm, University of Texas, Dallas

• Spatial Disparities, Selection, and Segmentation in Health Insurance - Presenting Author: Salpy Kanimian, Brown University

• Child Coverage Expansions: Spillover Effects on Health Insurance Among Citizen Children in Mixed-Status Families - Presenting Author: Mst Sadia Sadia Sultana, University of California, Irvine