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Health Aff (Millwood). 2018 Apr;37(4):591-599. doi: 10.1377/hlthaff.2017.1390.

Effects Of The ACA's Health Insurance Marketplaces On The Previously Uninsured: A Quasi-Experimental Analysis.

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Anna L. Goldman ( ) is a General Internal Medicine Fellow at Harvard Medical School and Cambridge Health Alliance, in Massachusetts.
Danny McCormick is an associate professor of medicine at Harvard Medical School and director of the Division of Social and Community Medicine in the Department of Medicine, Cambridge Health Alliance.
Jennifer S. Haas is a professor of medicine at Brigham and Women's Hospital, in Boston, Massachusetts.
Benjamin D. Sommers is an associate professor of health policy and economics in the Department of Health Policy and Management, Harvard T. H. Chan School of Public Health, and an associate professor of medicine at Brigham and Women's Hospital, both in Boston, Massachusetts.


Descriptive studies have suggested that the Affordable Care Act's (ACA's) health insurance Marketplaces improved access to care. However, no evidence from quasi-experimental studies is available to support these findings. We used longitudinal survey data to compare previously uninsured adults with incomes that made them eligible for subsidized Marketplace coverage (138-400 percent of the federal poverty level) to those who had employer-sponsored insurance before the ACA with incomes in the same range. Among the previously uninsured group, the ACA led to a significant decline in the uninsurance rate, decreased barriers to medical care, increased the use of outpatient services and prescription drugs, and increased diagnoses of hypertension, compared to a control group with stable employer-sponsored insurance. Changes were largest among previously uninsured people with incomes of 138-250 percent of poverty, who were eligible for the ACA's cost-sharing reductions. Our quasi-experimental approach provides rigorous new evidence that the ACA's Marketplaces led to improvements in several important health care outcomes, particularly among low-income adults.


Health Economics; Health Reform; Insurance; Insurance Coverage < Insurance; Insurance Market < Insurance


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