Has Medicare Part D Reduced Racial/Ethnic Disparities in Prescription Drug Use and Spending?

Objective To evaluate whether M edicare Part D has reduced racial/ethnic disparities in prescription drug utilization and spending. Data Nationally representative data on white, A frican A merican, and H ispanic M edicare seniors from the 2002–2009 M edical E xpenditure P anel S urvey are analyzed. Five measures are examined: filling any prescriptions during the year, the number of prescriptions filled, total annual prescription spending, annual out‐of‐pocket prescription spending, and average copay level. Study Design We apply the I nstitute of M edicine's definition of a racial/ethnic disparity and adopt a difference‐in‐difference‐in‐differences ( DDD ) estimator using a multivariate regression framework. The treatment group consists of Medicare seniors, the comparison group, adults without M edicare aged 55–63 years. Principal Findings Difference‐in‐difference‐in‐differences estimates suggest that for A frican A mericans Part D increased the disparity in annual spending on prescription drugs by $258 ( p  = .011), yet had no effect on other measures of prescription drug disparities. For H ispanics, DDD estimates suggest that the program reduced the disparities in annual number of prescriptions filled, annual total and out‐of‐pocket spending on prescription drugs by 2.9 ( p  = .077), $282 ( p  = .019) and $143 ( p  < .001), respectively. Conclusion Medicare Part D had mixed effects. Although it reduced Hispanic/white disparities related to prescription drugs among seniors, it increased the A frican A merican/white disparity in total annual spending on prescription drugs.