Race/ethnicity and nonadherence to prescription medications among seniors: Results of a national study

BACKGROUND: Nonadherence to prescription drugs results in poorer control of chronic health conditions. Because of significant racial/ethnic disparities in the control of many chronic diseases, differences in the rates of and reasons for medication nonadherence should be studied. OBJECTIVES: 1) To determine whether rates of and reasons for medication nonadherence vary by race/ethnicity among seniors; and 2) to evaluate whether any association between race/ethnicity and nonadherence is moderated by prescription coverage and income. DESIGN/SETTING: Cross-sectional national survey, 2003. PATIENTS: Medicare beneficiaries >= 65 years of age, who reported their race/ethnicity as white, black, or Hispanic, and who reported taking at least 1 medication (n=14,829). MAIN OUTCOME MEASURES: Self-reported nonadherence (caused by cost, self-assessed need, or experiences/side effects) during the last 12 months. RESULTS: Blacks and Hispanics were more likely than whites to report cost-related nonadherence (35.1%, 36.5%, and 26.7%, respectively, p <.001). There were no racial/ethnic differences in nonadherence caused by experiences or self-assessed need. In analyses controlling for age, gender, number of chronic conditions and medications, education, and presence and type of prescription drug coverage, blacks (odds ratio [OR] 1.38; 95% confidence interval [CI] 1.08-1.78) and Hispanics (1.35; 1.02-1.78) remained more likely to report cost-related nonadherence compared to whites. When income was added to the model, the relationship between cost-related nonadherence and race/ethnicity was no longer statistically significant (p=.12). CONCLUSIONS: Racial/ethnic disparities in medication nonadherence exist among seniors, and are related to cost concerns, and not to differences in experiences or self-assessed need. Considering the importance of medication adherence in controlling chronic diseases, affordability of prescriptions should be explicitly addressed to reduce racial/ethnic disparities.