Background: The purpose of this study was to examine selected measures of racial and ethnic disparities in the reported incidence of syphilis and gonorrhea from 1981 to 2013 in the United States.
Methods: For each year, from 1981 to 2013, we calculated values for 5 disparity measures (Gini coefficient, 2 versions of the index of disparity, population attributable proportion, and the black-to-white rate ratio) for 5 racial/ethnic categories (non-Hispanic white, non-Hispanic black, Hispanic, American Indian/Alaska Native, and Asian/Pacific Islander). We also examined annual and 5-year changes to see if the disparity measures agreed on the direction of change in disparity.
Results: With a few exceptions, the disparity measures increased from 1981 to 1993 and decreased from 1993 to 2013, whereas syphilis and gonorrhea rates decreased for most groups from 1981 to 1993 and increased from 1993 to 2013. Overall, the disparity measures we examined were highly correlated with one another, particularly when examining 5-year changes rather than annual changes in disparity. For example, all 5 measures agreed on the direction of change in the disparity of syphilis in 56% of the annual comparisons and in 82% of the 5-year comparisons.
Conclusions: Although the disparity measures we examined were generally consistent with one another, these measures can sometimes yield divergent assessments of whether racial/ethnic disparities are increasing or decreasing for a given sexually transmitted disease from one point in time to another, as well as divergent assessments of the relative magnitude of the change.