The rise and fall (and rise) of the Affordable Care Act: Varying impacts on coverage over time and place
Journal of Health Economics · 2026 · Gabriella N. Aboulafia、Jonathan Gruber A B、Benjamin D. Sommers
中文摘要
《平价医疗法案》（ACA）显著扩大了美国的医疗保险覆盖，但其影响因时间和各州而异。我们评估了该法自颁布以来（2013年至2023年间）在三届总统政府期间的异质性影响，以及在该法实施程度不同的各州之间的差异。我们重点关注该法的医疗补助扩展和市场补贴，包括2021年《美国救援计划》（ARP）下的增强补贴。我们使用全国家庭调查数据和三重差分设计——利用时间、地点和收入方面的变异——来识别该法关键组成部分的覆盖影响。我们发现，2013年至2023年间ACA相关覆盖增益中约50%来自市场补贴——其中约40%来自最初的ACA补贴，10%来自ARP增强补贴——其余一半则归因于医疗补助，包括“欢迎垫”效应。覆盖增益在不同总统政府间差异显著，市场补贴在奥巴马总统和拜登总统任内尤其比在特朗普总统任内更有效。同样的补贴金额在运营本州自建市场的州中，其效果是依赖联邦市场的州的1.5倍以上，且这一结果在考虑各州政治意识形态后依然成立。我们的发现突出表明，尽管ACA明确的经济特征推动了覆盖增益，但其有效性可通过联邦和州的实施而被大幅增强或阻碍。
Abstract
The Affordable Care Act (ACA) significantly expanded health insurance in the United States, but its impact has varied across time and states. We assess the law’s heterogeneous impacts over the three presidential administrations since its enactment (between 2013 and 2023), as well as across states with different levels of implementation of the law. We focus on the law's Medicaid expansion and Marketplace subsidies, including the enhanced subsidies under the American Rescue Plan of 2021 (ARP). We use national household survey data and a triple-difference design—leveraging variation by time, place, and income—to identify the coverage impacts of the key components of the law. We find that about 50% of ACA-related coverage gains between 2013 and 2023 came from Marketplace subsidies—about 40% from the original ACA subsidies and 10% from the ARP enhancements—while the remaining half were due to Medicaid, including from the "welcome mat" effect. Coverage gains differed substantially across presidential administrations, with Marketplace subsidies in particular proving more effective under Presidents Obama and Biden than under President Trump. The same subsidy amount was >1.5 times as effective in states running their own state-based Marketplaces than in states relying on the federal Marketplace, and this result persists even after accounting for states' political ideology. Our findings highlight that while the ACA’s explicit economic features drive coverage gains, their effectiveness can be substantially enhanced or hindered through federal and state implementation.