Articles & Working Papers

Harvard Open Access Depository – Selected publications available for free download.

Working Papers:

Fiscal Federalism and the Budget Impacts of the Affordable Care Act’s Medicaid Expansion
(joint with Jonathan Gruber, March 2020)
Abstract: Medicaid’s federal-state matching system of financing is the nation’s largest example of fiscal federalism. Using generous federal subsidies, the Affordable Care Act incentivized states to expand Medicaid, which became a state option in the aftermath of a 2012 Supreme Court ruling. As of early 2020, 14 states had not yet expanded, with concerns over state budgetary effects described as a key barrier. We use an event-study approach to analyze state budget data from 2010-2018 and assess the effects of state Medicaid expansion decisions. We find that Medicaid expansion increased total spending in expansion states by 6% to 9%, compared to non-expansion states. By source of funds, federal spending via the states increased by 10% in the first year of Medicaid expansion, rising to 27% in 2018. Changes in spending from state funding were modest and non-significant, with less than a 1% change from baseline annually in the most recent years, 2017 and 2018. Meanwhile, we find no evidence that increased Medicaid spending from expansion produced any reductions in spending on education, corrections, transportation, or public assistance. Changes in Medicaid spending tracked closely with the baseline pre-ACA (2013) uninsured rate in each states, with expansion leading to roughly $2680 in added annual spending per uninsured adult. As a result, we estimate states that didn’t expand Medicaid passed up $43 billion in federally-subsidized program funds in 2018. Finally, state projections in the aggregate were reasonably accurate, with expansion states projecting average Medicaid spending from 2014-2018 within 2 percent of the actual amounts, and in fact overestimating Medicaid spending in most years.

The Affordable Care Act’s Effects on Patients, Providers and the Economy: What We’ve Learned So Far (joint with Jonathan Gruber, June 2019)
Abstract: As we approach the tenth anniversary of the passage of the Affordable Care Act, it is important to reflect on what has been learned about the impacts of this major reform. In this paper we review the literature on the impacts of the ACA on patients, providers and the economy. We find strong evidence that the ACA’s provisions have increased insurance coverage. There is also a clearly positive effect on access to and consumption of health care, with suggestive but more limited evidence on improved health outcomes. There is no evidence of significant reductions in provider access, changes in labor supply, or increased budgetary pressures on state governments, and the law’s total federal cost through 2018 has been less than predicted. We conclude by describing key policy implications and future areas for research.

The Effect of State Medicaid Expansions on Prescription Drug Use: Evidence from the Affordable Care Act (joint with Ausmita Ghosh and Kosali Simon, January 2017)
Abstract: This study provides a national analysis of how the 2014 Affordable Care Act (ACA) Medicaid expansions have affected aggregate prescription drug utilization. Given the prominent role of prescription medications in the management of chronic conditions, as well as the high prevalence of unmet health care needs in the population newly eligible for Medicaid, the use of prescription drugs represents an important measure of the ACA’s policy impact. Prescription drug utilization also provides insights into whether insurance expansions have increased access to physicians, since obtaining these medications requires interaction with a health care provider. We use 2013-2015 data from a large, nationally representative, all-payer pharmacy transactions database to examine effects on overall prescription medication utilization as well as effects within specific drug classes. Using a differences-in-differences (DD) regression framework, we find that within the first 15 months of expansion, Medicaid-paid prescription utilization increased by 19 percent in expansion states relative to states that did not expand; this works out to approximately seven additional prescriptions per year per newly enrolled beneficiary. The greatest increases in Medicaid prescriptions occurred among diabetes medications, which increased by 24 percent. Other classes of medication that experienced relatively large increases include contraceptives (22 percent) and cardiovascular drugs (21 percent), while several classes more consistent with acute conditions such as allergies and infections experienced significantly smaller increases. As a placebo test, we examine Medicare-paid prescriptions and find no evidence of a post-ACA effect. Both expansion and non-expansion states followed statistically similar trends in Medicaid prescription utilization in the pre-policy era, offering support for our DD approach. We did not observe reductions in uninsured or privately insured prescriptions, suggesting that increased utilization under Medicaid did not substitute for other forms of payment. Within expansion states, increases in prescription drug utilization were larger in geographical areas with higher uninsured rates prior to the ACA. Finally, we find some suggestive evidence that increases in prescription drug utilization were greater in areas with larger Hispanic and black populations.

Premium Subsidies, the Mandate, and Medicaid Expansion: Coverage Effects of the Affordable Care Act (joint with Molly Frean and Jonathan Gruber, April 2016, Revised November 2016)
Abstract: Using premium subsidies for private coverage, an individual mandate, and Medicaid expansion, the Affordable Care Act (ACA) has increased insurance coverage. We provide the first comprehensive assessment of these provisions’ effects, using the 2012-2015 American Community Survey and a triple-difference estimation strategy that exploits variation by income, geography, and time. Overall, our model explains 60% of the coverage gains in 2014-2015. We find that coverage was moderately responsive to price subsidies, with larger gains in state-based insurance exchanges than the federal exchange. The individual mandate’s exemptions and penalties had little impact on coverage rates. The law increased Medicaid among individuals gaining eligibility under the ACA and among previously-eligible populations (“woodwork effect”) even in non-expansion states, with essentially no crowd-out of private insurance. Overall, exchange premium subsidies produced 40% of the coverage gains explained by our ACA policy measures, and Medicaid the other 60%, of which 1/2 occurred among previously-eligible individuals.