Medicare Part D and its impact on racial/ethnic disparities in access to prescription medications

Objectives. This study evaluates the impact of Medicare Part D on racial/ethnic disparities in access to prescription medications. This paper seeks to answer four questions: (1) Has Medicare Part D increased access to prescription drugs within different racial/ethnic groups, and if so, by how much? (2) Has Medicare Part D reduced racial/ethnic disparities in access to prescription drugs? (3) Has Medicare Part D reduced disparities in out-of-pocket and total spending on prescription drugs, and in out-of-pocket and total healthcare spending? And (4) Do the answers to these questions vary when different definitions for a “disparity” are used, and if so, how? Data. Medical Expenditure Panel Survey (MEPS) data covering 2003 through 2008 will be used for the analysis. Six measures of access will be examined: whether an individual has prescription drug insurance, the number of prescriptions actually filled during the year, annual out-of-pocket and total spending on prescription medications, and annual out-of-pocket and total healthcare spending. The “treatment group” will consist of MEPS respondents ages 65-70, and the “comparison group” will consist of MEPS respondents ages 59-64. Methods. A “pre-post-with-comparison-group” quasi-experimental design will be implemented using the framework of multivariate regression analysis. Specifically, a regression-based difference-in-differences (DD) estimator will be adopted to quantify Medicare Part D's effects on each of the six outcome measures. Three alternative definitions for a “disparity” between a minority group and Whites will be explored, specifically, the AHRQ definition, the IOM definition, and a third one, called the “Residual Direct Effect” definition in the literature.