Sexual mixing patterns and heterosexual HIV transmission among African Americans in the southeastern United States.

OBJECTIVES: Heterosexually transmitted HIV infection rates are disproportionately high among African Americans. HIV transmission is influenced by sexual network characteristics, including sexual partnership mixing patterns among subpopulations with different prevalences of infection. STUDY
DESIGN: We conducted a cross-sectional analysis of previously collected data from a North Carolina population-based case-control study. Respondents were heterosexual black men and women who either had recently reported heterosexually transmitted HIV infection (cases) or were randomly selected from the general population (controls).
METHODS: Respondents reported their own and their 3 most recent sex partners' education and involvement in illicit drug use, concurrent sex partners, and incarceration. We examined sexual mixing patterns by comparing the characteristics and behaviors of respondents reported for themselves with those they reported for their partners. We estimated Newman assortativity coefficient (-1.0 to 1.0) as an aggregate quantitative assessment of mixing patterns.
RESULTS: Across the 4 strata (male and female cases, male and female controls), mixing was assortative (0.31-0.45) with respect to illicit drug use and minimally assortative with respect to having concurrent partners (0.14-0.22). Mixing patterns for incarceration were assortative for men (0.18 and 0.41) but not women (0.07 and 0.08). Mixing with respect to education was assortative primarily for male controls (0.33).
CONCLUSIONS: These sexual partnership patterns, driven in part by the social and economic context of life for African Americans, likely contribute to the heterosexually transmitted HIV epidemic.