Illicit drug use and risk of HIV seroconversion among gay men in Sydney: data from the HIM cohort
Background: Illicit drug use has been associated with risk behaviour among gay men. We examined frequency of use of illicit drugs as a risk factor for HIV seroconversion in a community-based cohort of HIV negative homosexually active men in Sydney, Australia.
Methods: From June 2001 to June 2007, participants underwent annual HIV testing and were interviewed twice a year. Detailed information about sexual, drug-using and other behaviour was collected.
Results: Among 1,427 participants enrolled, 53 HIV seroconverters were identified by June 2007. At baseline, 62.7% reported using illicit drugs in the previous six months, including 10.7% who reported at least weekly use. Illicit drug use was associated with unprotected anal intercourse with casual partners (UAIC) (p<.001). More frequent drug use was also associated with being younger, more frequent participation in gay party scenes, and being more ‘sexually adventurous’. Use of a range of illicit drugs significantly increased the risk of HIV infection at a univariate level and this risk increased with greater frequency of use: Amyl nitrite (p-trend=0.001); cocaine (p-trend=0.005); ecstasy (p-trend=0.031); methamphetamine (p-trend<0.001). After controlling for number of UAI episodes according to partners’ HIV status, more frequent use of methamphetamine (HR1.34; CI 1.01-1.78) and amyl nitrite (HR1.30 CI 1.02-1.67) remained significant.
Conclusion: While drug use may not be a directly causative factor for UAIC, in this cohort of HIV-negative gay men frequent drug use, particularly methamphetamine and amyl nitrite, is independently associated with HIV seroconversion. Both amyl nitrite and methamphetamine are often used specifically to enhance sexual pleasure among gay men. The association between these drugs and risk among gay men suggests that intensive sex partying, where both these activities often occur, is an appropriate priority in HIV-prevention efforts in this population.
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