This dissertation consists of essays on the causal impact of public health insurance
policies in the United States. Three chapters investigate how Medicare program, Medicare
Prescription coverage program, and the Affordable Care Act Medicaid expansion impact on
health-related outcomes, health care expenditure, and food wellbeing.
The first chapter in this dissertation examines the causal treatment effects of Medicare on
health care utilization and cost among the elderly. We provide new estimates of the impact of
Medicare on healthcare utilization, including office-based and outpatient, hospital inpatient, and
emergency department visits. We exploit the discontinuity in health insurance coverage rates at
the Medicare eligibility age of 65 to investigate the impact of Medicare on health care utilization
and spending among the elderly. We find that the discrete change in insurance coverage rates at
age 65 leads to a significant increase in office-based physician and outpatient visits, which is
mainly driven by those who were not insured before age 65. We also document that the Medicare
eligibility at age 65 is associated with up to 40 percent decrease in out-of-pocket spending for
physician and outpatient visits. On the other hand, we find that Medicare eligibility does not
have a significant impact on the utilization of inpatient or emergency department services.
The second chapter studies the impact of Medicare prescription drug coverage on out of
pocket spending and food access among the elderly in the US. Prescription drugs were first
included in Medicare in 2006, under the Medicare Modernization Act. We use data from the
Health and Retirement Study(HRS) wave 2000-2014 with a difference-in-difference-indifference approach by comparing the variation in the outcome of seniors aged 66-70 and younger seniors aged 60-64, before and after Medicare Part D, and across health status. The
estimation indicated that Medicare Part D is associated with an increase in the probability of having enough money for food, an increase in the weekly spending for food, and a reduction in
the SNAP participation among lone seniors with multiple chronic conditions. We also find
evidence of an increase in the probability of report having enough money for food among couple
seniors families aged over 65 but in smaller magnitude.
The third chapter explores the impact of 2014 Medicaid expansions under the Affordable
Care Act (ACA) on the utilization for diabetes among low-income childless adults. The
Medicaid expansion aims to provide Medicaid coverage to the low-income population regardless
of parent or age. We use difference-in-difference design to compare the outcomes in expansion
states with non-expansion states before and after 2014. Our estimation suggested evidence that
Medicaid expansions lead to more appropriate in particular care for diabetes but not all; and
improvement in self-accessed health outcomes among people with diabetes.