Background: Racial/ethnic disparities in sexually transmitted infection (STI) diagnosis and prevalence exist in the United States. Black Americans bear a disproportionate share of the overall STI burden; this could reflect individual risk behaviors or broader contextual factors. Characterizing sexual behavior and mixing patterns is important for modeling STI dynamics. We used national survey data to analyze self-reported sexual partnership behaviors in adults aged 15-39y, and to identify differences by race/ethnicity.
Methods: Ever sexually-active respondents in the 2011-2013 National Survey of Family Growth (n=7511) and their most recent opposite-sex sexual partner were categorized as non-Hispanic black, Hispanic, or other (including all other race/ethnicity categories), and subdivided by age (15-24y and 25-39y). We compared group differences in recent and lifetime partners and in propensity to partner with members of the same race/ethnicity or age group (i.e. to mix assortatively) using ANOVA and χ2 tests.
Results: Non-Hispanic black males reported more lifetime sexual partners and partners in the past year than Hispanic and other males (p<0.001). Hispanic females reported fewer lifetime partners than black and other females (p<0.001), while sexual partner numbers in the past year did not differ by race/ethnicity amongst females (p=0.89). Hispanic females were less likely to report a most recent sexual partner of the same race/ethnicity (63%) than black (89%) or other (86%) females (p<0.001). Black (77%) and Hispanic (72%) males were less likely to report assortative mixing by race/ethnicity than other (89%) males (p<0.001). Similar trends in racial/ethic assortativity were observed across age categories. Age-assortative mixing was more common among older females and younger males than among younger females and older males (p<0.001), and did not differ by ethnicity.
Conclusions: Self-reported sexual behaviors differ by race/ethnicity and age in the United States. This information can inform mathematical models of STI transmission and help illuminate behavioral drivers of observed disparities in STI burden.