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.

我们使用全面的患者出院数据来研究医疗补助对医院服务使用的影响。我们的分析依赖于《平价医疗法案》的医疗补助扩展中的州际差异，以及邮政编码在扩展中的州内差异。我们发现，医疗补助计划的扩大增加了医疗补助计划的就诊次数，并减少了无保险的就诊次数。净效应对所有就诊都是积极的，这表明那些通过医疗补助获得覆盖的人比没有保险的人享受更多的医院服务。急诊就诊的增加主要是由于“可延误”的医疗状况造成的。在Medicaid扩展计划下获得覆盖的人似乎是对医院服务的需求相对较高的人，这表明扩展计划的针对性很强。最后，我们发现，在扩张的影响下，医疗补助扩张州之间存在显着的异质性，有些州的总利用率大大提高，而另一些州的变化却很小。在医疗补助扩张的州中，医院利用率的增长幅度更大，该州有更多的居民获得保险，并且扩张前的未补偿医院护理费用水平较低。