Racial differences in medication adherence: A cross-sectional study of Medicare enrollees

Background: Racial differences in adherence to prescribed medication regimens have been reported among the elderly. It remains unclear, however, whether these differences persist after controlling for confounding variables.

Objective: The objective of this study was to determine whether racial differences in medication adherence between African American and white seniors persist after adjusting for demographic characteristics, health literacy, depression, and social support. We hypothesized that differences in adherence between the 2 races would be eliminated after adjusting for confounding variables.

Methods: A survey on medication adherence was conducted using face-to-face interviews with Medicare recipients >or=65 years of age living in Chicago. Participants had to have good hearing and vision and be able to speak English to enable them to respond to questions in the survey and sign the informed-consent form. Medication adherence measures included questions about: (1) running out of medications before refilling the prescriptions; (2) following physician instructions on how to take medications; and (3) forgetting to take medications. Individual crude odds ratios (CORs) were calculated for the association between race and medication adherence. Adjusted odds ratios (AORs) were calculated using the following covariates in multivariate logistic regression analyses: race; age; sex; living with a spouse, partner, or significant other; income; Medicaid benefits; prescription drug coverage; having a primary care physician; history of hypertension or diabetes; health status; health literacy; depression; and social support.

Results: Six hundred thirty-three eligible cases were identified. Of the 489 patients who responded to the survey, 450 (266 African American [59%; mean age, 78.2 years] and 184 white [41%; mean age, 76.8 years]; predominantly women) were included in the sample. The overall response rate for the survey was 77.3%. African Americans were more likely than whites to report running out of medications before refilling them (COR = 3.01; 95% CI, 1.72-5.28) and not always following physician instructions on how to take medications (COR = 2.64; 95% CI, 1.50-4.64). However, no significant difference between the races was observed in forgetting to take medications (COR = 0.90; 95% CI, 0.61-1.31). In adjusted analyses, race was no longer associated with low adherence due to refilling (AOR = 1.60; 95% CI, 0.74-3.42). However, race remained associated with not following physician instructions on how to take medications after adjusting for confounding variables (AOR = 2.49; 95% CI, 1.07-5.80).

Conclusion: Elderly African Americans reported that they followed physician instructions on how to take medications less frequently than did elderly whites, even after adjusting for differences in demographic characteristics, health literacy, depression, and social support.