Substance use and high-risk sex among people with HIV: a comparison across exposure groups.

Substance use is associated with increased risk for HIV transmission by HIV-positive people to uninfected partners through sexual contact. The largest risk groups for infection, men who have sex with men (MSM) and injecting drug users (IDUs), have high rates of substance use, but little is known about their substance use post-HIV diagnosis. We compared the prevalence of substance use between these two groups and a third group, heterosexual men and women, and tested for differential association between substance use and sexual behaviors across exposure groups in a national sample of patients in treatment for HIV. Substance use was most prevalent among MSM. Substance use and current dependence were associated with being sexually active among MSM but not IDUs; marijuana, alcohol, and hard drug use were most strongly associated with being sexually active among MSM. Whereas substance use predicted high-risk sex, there were few differences among exposure groups in these associations.