The racial disparities in STI in the U.S.: Concurrency, STI prevalence, and heterogeneity in partner selection

• STIs are more prevalent among Blacks than Whites.
• Differences in individual-level risk behaviors do not explain the disparity.
• Partner concurrency and assortative mixing are significantly associated with STI.
• Differences in network structure may account for part of the racial disparity in STI.

BackgroundThere is a large and persistent racial disparity in STI in the U.S. which has placed non-Hispanic-Blacks at disproportionately high risk. We tested a hypothesis that both individual-level risk factors (partner number, anal sex, condom use) and local-network features (concurrency and assortative mixing by race) combine to account for the association between race and chlamydia status.MethodsData from the Longitudinal Survey of Adolescent Health Wave III were used. Chlamydia status was determined using biomarkers. Individual-level risk behaviors were self-reported. Network location variables for concurrency and assortative mixing were imputed using egocentrically sample data on sexual partnerships.ResultsAfter controlling for demographic attributes including age, sex, marital status, education and health care access there remained a strong association between race and chlamydia status (OR = 5.23, 95% CI [3.83–7.15], p < .001 for Non-Hispanic Blacks with Non-Hispanic Whites as the reference category). The inclusion of individual-level risk factors did not alter the association between race and chlamydia (OR = 5.23 for Non-Hispanic Blacks). The inclusion of concurrency and assortative mixing by race substantially reduced the association between race and chlamydia status (OR = 1.87, 95% CI [0.89–3.91] p > .05 for Non-Hispanic Blacks).