Racial/ethnic disparities in access to prescription drugs during early years of drug products' life cycles

Abstract

Objectives: To determine whether there are racial/ethnic disparities in the utilization of all new prescription drugs, and new, essential drugs. Methodology: The main data source was Medical Expenditure Panel Survey (1996--2001). Drugs were considered "new" if they had been in the market for less than six years. They were considered essential if at least four out of five experts considered them "essential". A negative binomial model was used to test the disparities in the average numbers of all new prescribed medicines or new, essential prescribed medicines across racial/ethnic groups when controlling for socioeconomic confounders. Sensitivity analyses were performed using variable definitions for the number of years post-launch that a drug is considered new and using relaxed criterion for essential drugs. Results: Among 47,115 prescription users, 31,853 were non-Hispanic whites, 5,904 were non-Hispanic blacks, and 7,337 were white Hispanics. The disparities in the use of all new drugs generally were significant between non-Hispanic whites and non-Hispanic blacks both before and after adjusting for confounding factors; this aspect of disparities were significant between non-Hispanic whites and white Hispanics before adjustment but they were not always significant afterwards. The disparities in the use of new, essential drugs were not significant between non-Hispanic whites and non-Hispanic blacks before adjusting for confounding factors but they were significant afterwards; this aspect of disparities between non-Hispanics whites and white Hispanics were significant before the adjustment but they generally were not significant afterwards. Gaps in the use of new, essential drugs was narrower than gaps in the use of all new drugs. Generosity of drug coverage and self-perceived worse health status had positive effects on the use of all new drugs and new, essential drugs. Sensitivity analyses reported similar results. Conclusions: There are smaller racial/ethnic disparities in the use of all new, essential drugs than the use of all new drugs. Larger share of ethnic disparities is accounted for by socioeconomic factors than racial disparities. The generosity of drug insurance coverage and self-perceived worse health status are positively correlated with the use of all new drugs and new, essential drugs.