Racial and Ethnic Differences in Medication Adherence and Medicare Part D: A Longitudinal Comparison

Background and Purpose: Pharmaceuticals are an increasingly essential part of treatment for chronic conditions among the older adult population. However, prescription drug costs can be a barrier to medication access and prevent older individuals from maintaining adherence. Prior to Medicare Part D, older Blacks and Hispanics reported greater cost-related medication nonadherence (CRN) compared to older non-Hispanic Whites. While overall the benefit helped facilitate the purchase of needed medications, the viability of Medicare Part D as a means of reducing or eliminating racial and ethnic disparities in CRN remains uncertain. Using cumulative advantage/disadvantage theory as a framework, this longitudinal study examined 1) whether racial and ethnic disparities in CRN have changed since Medicare Part D, 2) whether socioeconomic status and health status mediate the relationship between race, ethnicity, and CRN over time, and 3) whether socioeconomic status and health status directly affect CRN over time.

Methods:  This study utilized secondary data from the 2004, 2006, and 2008 waves of the Health and Retirement Study (HRS) and data from the 2005, 2007, and 2009 waves of the Prescription Drug Study (PDS), a subsample of the HRS, to evaluate changes in CRN before and after Medicare Part D. The analytic sample consisted of 1,672 respondents age 65 and older that were Medicare-eligible, taking at least one prescribed medication, and responded to questions about adherence or nonadherence. The outcome variable of interest was CRN, which included not filling, stopping, or skipping doses of a prescription because of cost. The main predictors were race (Black American and non-Hispanic White) and ethnicity (Hispanic). Covariates included demographics, socioeconomic status, and health status. The analysis was conducted using mixed-effects logistic regression models.

Results:  Results indicated that older Blacks and Hispanics were significantly more likely to report CRN both before and after Medicare Part D compared to older non-Hispanic Whites. While the rate of CRN for older Hispanics significantly decreased over time in comparison to older non-Hispanic Whites, there was no change in the rate for Black Americans relative to non-Hispanic Whites. The introduction of variables related to socioeconomic and health status did not affect racial differentials; however, annual household income mediated ethnic differences in CRN. Further, having a lower annual income, poorer self-reported health, or a greater number of chronic conditions had a direct effect on CRN before and after Medicare Part D.

Conclusions and Implications:  Racial and ethnic disparities in CRN continue to persist despite the establishment of a drug benefit under Medicare. Ethnic differences in CRN were substantially driven by annual household income, suggesting that costs associated with the benefit may be particularly difficult for older Hispanics given their earnings are typically lower. Further, socioeconomic status and health status continue to impact medication adherence. Understanding how Medicare Part D has affected adherence can help social work practitioners recognize that clients may need additional resources and assistance in order to avoid CRN. Additionally, findings help substantiate the need to account for race and ethnicity when evaluating policy alternatives in order to promote more equitable access to medications.