Measures of racial disparity in rates of sexually transmitted disease

Background: Although relative measures are commonly used to express health disparities, absolute measures could have more value in public health decision-making. Goal: The goal of this study was to examine how associations between county-level variables and black-white racial disparity in gonorrhea rates varied by the measure of disparity used. Study Design: We studied correlations of 10 population-level variables with the incidence rate difference (RD) and incidence rate ratio (RR) of gonorrhea in North Carolina (NC) counties. Results: Nine of the 10 variables correlated more strongly with the RD than the RR. The RD was highly correlated with incidence rates of gonorrhea among blacks (r > 0.99). Conclusion: Several county-level variables were correlated with absolute, but not with relative, racial disparity in gonorrhea in NC. Disease rates were so disparate that the RD essentially reflected rates in the black population. The RD should be preferentially used in planning and evaluating interventions aimed at eliminating racial disparities in gonorrhea in NC.