RACIAL DISPARITIES ON EXPENDITURES OF PRESCRIPTION MEDICATION FOR MAJOR CHRONIC DISEASES IN THE U.S.: MEDICAL EXPENDITURE PANEL SURVEY 2011-2012

Purpose: Racial disparities in health outcomes is a severe public health concern.  This study explores whether there are also racial disparities in medication expenditures for five major chronic diseases (diabetes, heart diseases, cancers, mental disorders, and chronic respiratory diseases) among non-institutionalized U.S. adults.

Method: We used data from the Medical Expenditure Panel Survey, 2011-2012, to study racial differences (white, black, Asian, Hispanic and other) in (1) annual medication expenditures, and (2) the number of visits that included medical prescriptions for major chronic diseases (prescription visits). The annual medication expenditures were estimated using two-part models, with logistic regression in the first part and generalized linear model with log-link and gamma variance in the second part. The number of prescription visits was estimated using zero-inflated Poisson model. Covariates included age, age squared, gender, logged total family income, education (<high school, high school diploma, college, graduate school), insurance status (private, Medicaid, Medicare, uninsured, and other public insurance), census region, and body mass index category. Complex sampling designs were adjusted for. All dollar values are expressed in 2012 US prices.

Result: Whites had significantly larger predicted medication expenditures and number of prescription visits than other races for most major chronic diseases in our study (all ps<.05). Across all five diseases, diabetes had the highest racial differentials in medication expenditures and number of prescription visits. Averaging over all non-white races, the medication expenditures differentials for non-whites compared to whites was -$1,279 for diabetes, -$812 for chronic respiratory diseases, -$466 for mental illness, -$444 for heart diseases, and -$433 for cancer. Compared to whites, non-whites had fewer prescription visits: -8.7 for diabetes, -6.3 for chronic respiratory diseases, -5.6 for mental illness, -4.7 for cancer, and -4.0 for heart diseases. Averaging over all five diseases, Asians had the largest differences in medical expenditures and number of visits with medical prescription with the whites, followed by blacks and Hispanics.

Conclusion: There are substantial racial differences in the predicted medication expenditures and number of visits with medical prescriptions for five major chronic diseases in the U.S., even controlling for key covariates. Future research should examine the causes of these disparities and the extent to which disparities in medical expenditures contribute to racial disparities in morbidity and mortality outcomes.