Relationship between heterosexual anal sex, injection drug use and HIV infection among black men and women.

US blacks carry a disproportionate risk of heterosexually transmitted HIV. This study aimed to evaluate the association between self-reported heterosexual anal intercourse and HIV. Using respondent-driven sampling (RDS), we recruited and interviewed 909 blacks from areas of high poverty and HIV prevalence in Houston, Texas, and who reported heterosexual sex in the last year. All individuals were tested for HIV. Weighted prevalence values were calculated to account for non-random recruitment associated with RDS. The weighted population prevalence of HIV infection was 2.4% and 2.5% among men and women, respectively. Education, employment status, income and crack cocaine use were not associated with HIV infection. Lifetime injection drug use (odds ratio [OR] 3.31, 95% confidence interval [CI] 1.31-8.33%) and heterosexual anal intercourse (OR 2.41, 95% CI 1.02-5.73%) were associated with HIV infection. Individuals who reported both injection drug use and heterosexual anal intercourse had 6.21 increased odds of HIV (95% CI 2.47-15.61%). Our results suggest that heterosexual anal sex may be a vector for HIV transmission, especially in the context of injection drug use. Prevention strategies directed at curbing the HIV epidemic among black heterosexuals require that we correctly identify the risks so that appropriate interventions can be developed.