Victoria R. Marone

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...

A health insurer's Medical Loss Ratio (MLR) is the share of premiums spent on medical claims. The Affordable Care Act introduced minimum MLR provisions for all health insurance sold in fully-insured commercial markets, thereby capping insurer profit margins, but not levels. While intended to reduce premiums, we show this rule creates incentives analogous to cost of service regulation. Using variation created by the rule's introduction as a natural experiment, we find claims costs rose nearly one-for-one with distance below the regulatory threshold: 7% in the individual market, and 2% in the group market. Premiums were unaffected.