A summary measure of health disparity.

OBJECTIVES Eliminating health disparities is a goal of Healthy People 2010. In order to track progress toward this goal, we need improved methods for measuring disparity. The authors present the Index of Disparity (ID) as a summary measure of disparity. METHODS The ID, a modified coefficient of variation, was used to measure disparity across populations defined on the basis of race/ethnicity, income, education, and gender. Disparity was also assessed for a diverse range of health indicators and over time to monitor trends. RESULTS Disparity in cardiovascular disease deaths decreased based on gender from 1989 to 1998 but was largely unchanged based on race/ethnicity. The magnitude of disparities in cervical cancer and cholesterol screening, smoking, exercise, and health insurance ranged from 1.9% to 78.6%. The largest disparities for health indicators were not associated with any particular population classification, whether defined on the basis of race/ethnicity, education, or income. CONCLUSIONS To eliminate disparities, we need a means to assess disparities across many types of health indicators. Furthermore, for a given health indicator, disparities may differ for populations defined on the basis of race/ethnicity, education, income, and so on. The ID is a simple method for summarizing disparities across groups within a population that can be applied across health indicators regardless of magnitude, over time to monitor trends, and across different populations.