All Medicaid Expansions Are Not Created Equal: The Geography and Targeting of the Affordable Care Act
利用患者层面数据，研究《平价医疗法案》下医疗补助扩展对医院服务使用的影响，发现扩展增加了医疗补助就诊、减少了无保险就诊，且急诊增加主要由可推迟病症驱动，扩展目标定位良好但各州效果差异显著。
We use comprehensive patient-level discharge data to study the effect of Medicaid on the use of hospital services. Our analysis relies on cross-state variation in the Affordable Care Act's Medicaid expansion, along with within-state variation across zip codes in exposure to the expansion. We find that the Medicaid expansion increased Medicaid visits and decreased uninsured visits. The net effect is positive for all visits, suggesting that those who gain coverage through Medicaid consume more hospital services than they would if they remained uninsured. The increase in emergency department visits is largely accounted for by "deferrable" medical conditions. Those who gained coverage under the Medicaid expansion appear to be those who had relatively high need for hospital services, suggesting that the expansion was well targeted. Lastly, we find significant heterogeneity across Medicaid expansion states in the effects of the expansion, with some states experiencing a large increase in total utilization and other states experiencing little change. Increases in hospital utilization were larger in Medicaid expansion states that had more residents gaining coverage and lower pre-expansion levels of uncompensated hospital care costs.