This dissertation comprises three discrete empirical papers, with an introductory essay that evaluates the impact of different federal policies on prescription drug prices, utilization, and spending. Two main databases are used: (a) Medicaid State Drug Utilization Data and (b) the Medical Expenditure Panel Survey (MEPS) data. These two databases are designed to track Medicaid drug utilization and overall medical use and expenditures, respectively. The variables of interest in this dissertation are prescription drug price, prescription drug use and spending, and overall drug expenditures. The objective of the first paper (Chapter 2) is to examine whether oncology drug prices have significantly changed because the Medicaid rebate increased under the Patient Protection and Affordable Care Act (ACA). The analytic sample includes top-selling oncology drugs, both branded and generic, over an 8-year time period. The prices of top-selling oncology drugs in 2006 were followed through 2013 to find the extent to which drug prices have changed while controlling for state fixed-effect, package size, type of manufacturer, brand or generic, and drug strength. Thus, this study examines whether and to what extent oncology drug prices have changed after the increase in the Medicaid rebate under the ACA. The second paper’s objective (Chapter 3) is to study whether Medicare Part D has reduced racial disparities in diabetes drug use, coverage, and spending since its implementation in 2006. The analytic sample includes individuals aged 55 years and older who had diabetes from 2001 to 2010. Although the impact of Medicare Part D has been studied from different perspectives, its impact on racial disparities in drug use, coverage, and expenditures among diabetics has not been studied yet. The third paper (Chapter 4) focuses on the association between closing the Medicare doughnut hole and prescription drug utilization and spending for Medicare Part D beneficiaries with chronic diseases through 2013. The objective of the third paper is to determine whether the provisions of the ACA that close the coverage gap have affected prescription drug utilization and out-of-pocket (OOP) spending among Medicare seniors with Part D coverage.

INTRODUCTION: Medicare Part D provides prescription drug coverage to seniors through a benefit plan with a major deductible inserted in the middle. It is important to study the extent to which this structure affects seniors’ adherence to prescription medications. Therefore, this study had the following objectives: (1) To identify characteristics of beneficiaries reaching and not reaching the coverage gap, (2) To study the entry and exit times from the coverage gap, (3) To study the impact of a complete gap in coverage on beneficiaries’ adherence to prescription medications, (4) To study the impact of a partial gap in coverage on beneficiaries’ adherence to prescription medications METHODS: This was a retrospective quasi-experimental analysis with matched control groups using a nationally representative sample of Part D enrollees from 2008 Centers for Medicare and Medicaid (CMS) datasets. Adherence to each oral medication taken for one or more of the seven pre-defined therapeutic classes before and after reaching the coverage gap was measured using the Medication Possession Ratio (MPR). Appropriate statistical tests for significance were performed for each analysis RESULTS: A quarter of our sample (24.42%) reached the coverage gap in 2008. Most of the beneficiaries reaching the coverage gap did so by end of September. Those reaching the coverage gap and losing all coverage experienced significantly greater reductions in adherence (3% more for beta-blockers to 9% more for oral anti-diabetic agents), compared to those not reaching the coverage gap. A considerable proportion of beneficiaries stopped taking medications in both the groups and the proportion of beneficiaries considered adherent also dropped in both the groups during the coverage gap period. CONCLUSIONS: Medicare Part D beneficiaries face significant barriers to adherence and this is especially highlighted among those reaching the coverage gap. Interventions to improve adherence in this group should target all beneficiaries, especially those with several chronic conditions.