Associations between crystal methamphetamine use and potentially unsafe sexual activity among gay men in Australia

It has been suggested that crystal methamphetamine may have disinhibiting or aphrodisiac effects, which may lead to unsafe sexual behavior and increase the risk of HIV transmission. Using data from two Australian studies, the Sydney Gay Community Periodic Survey study and the Positive Health (PH) cohort study, we examined changes over time in use of crystal, other recreational drugs, and Viagra, and in a range of sex-related behaviors. Compared to non-users, crystal users reported having more sex partners, looking for sex in more types of venues, and being more likely to engage in unprotected anal intercourse with casual partners (UAIC) and in esoteric sex. Crystal users were also more likely to be using other recreational drugs and Viagra than non-users. Crystal use remained significantly associated with UAIC after adjustment for other relevant variables in a log-binomial regression analysis (adjusted prevalence rate ratio=1.26; 95% CI: 1.19-1.34). The other variables (HIV status, number of sex partners, number of types of venue where men looked for sex, Viagra use, other drug use) were independently associated with UAIC, and did not show confounding or mediating effects on the crystal-UAIC association. Nevertheless, these data did not allow reliable attribution of higher levels of these sex-related behaviors among crystal users specifically to the effects of crystal. The prevalence of crystal use among Australian men who have sex with men (MSM) increased between 2002 and 2005 (e.g., from 26% to 39% among HIV-+ MSM). However, the prevalence of UAIC remained stable or decreased over time in various study subgroups, as did the prevalence of other sex-related behaviors, suggesting that crystal use does not necessarily drive unsafe sexual behavior. Crystal use and unsafe sexual behavior can, and should, be considered and addressed separately in health promotion and community education campaigns.