Essays on Insurance Policies and Medication Use

This dissertation examines the causal impacts of insurance policies and medication use on health and economic outcomes. Using various econometric methods, I evaluate and quantify the effects of several state and federal health policies. Chapter 1 examines the effect of prior authorization (PA) of Truvada (emtricitabine/tenofovir) for pre-exposure prophylaxis (PrEP) on Truvada utilization, expenditure, and sexually transmitted infections (STIs). Between 2012–2013, six state Medicaid programs implemented PrEP PA as a strategy for reducing drug expenditures. Using a two-way fixed effects model, I find that PrEP PA led to a significant decrease in Truvada expenditure and no changes in STI outcomes. Chapter 2 examines the effect of the Veterinary Feed Directive (VFD) that eliminated the use of medically important antibiotic drugs in livestock on antibiotic-resistant hospital acquired infections (AR HAIs). Using an interrupted time-series design, I find that the VFD was significantly associated with a 10.5% decrease in methicillin-resistant Staphylococcus aureus (MRSA) infections (p = 0.005) and a 42.0% decrease in Clostridioides difficile infections (CDIs; p = 0.003). Stratified analysis of hospitals by rural status showed a greater reduction in the rates of AR HAIs in rural counties, suggesting that AR HAIs is driven mainly by transmission from proximity contact between humans and livestock/livestock byproducts. Chapter 3 expands upon the findings in Chapter 2 by examining the effect of livestock quantity, density, and type on AR HAIs using an instrumental variable approach. These findings not only fill an important gap in knowledge regarding the effects of these policies but are also crucial in informing policymaking and cost-benefit considerations. Lastly, it is important to recognize the effect that animal, environmental, and human health have on each other, and to consider future studies and policies with the One Health perspective in mind.