Gay men who engage in unprotected anal intercourse with a regular partner, who they believe to be HIV-negative, are not at increased risk of HIV infection according to data from the Sydney Men and Sexual Health Study (SMASH). Presented by Dr Andrew Grulich at the recent Conference of the Australasian Society for HIV Medicine, the study confirms that the `negotiated safety' approach to safer sex education does not necessarily lead to an increased incidence of HIV infection.
However, men who have unprotected anal intercourse (UAI) with casual partners, regardless of their perceived HIV status, are at risk of infection. Furthermore, the risk increases with the number of casual partners. The SMASH study authors concluded that negotiating unsafe sex with casual partners is a risky strategy.
Not surprisingly, UAI with an HIV-positive regular partner was also associated with an increased risk of HIV infection.
The SMASH study enrolled 701 gay men in 1992. Annual interviews and HIV testing showed that 30 seroconverted with HIV between 1993-1997, mostly during the early years of the study. Between 10-15% of men reported UAI during any six-month period.
Dr Grulich was reluctant to attribute the decline in HIV infections over time to the introduction of combination antiretroviral therapy. "In many cohort studies looking at the risk of HIV you get a predominance of infections in the first few years because the people at high risk rapidly become infected, while the rest continue to be at low risk," Dr Grulich said.
In addition to UAI with a casual or HIV-infected partner, other high-risk behaviours were sex work and the use of drugs such as ecstasy, speed, marijuana, LSD and amyl nitrate. Injecting drug use also increased the risk of seroconversion.
Men in relationships for less than one year were more likely to be infected with HIV than men in long-term relationships. According to Dr Grulich, "It’s probably due to the failure of negotiated safety during early relationship formation. For example, people have unprotected anal intercourse before they are certain about their partner’s status, or they fall in love and forget about condom use".
Another new finding of the study was a link between seroconversion and socio-economic status. Gay men on low incomes or in "blue collar" jobs were more likely to contract HIV than wealthier gay men in professional jobs.
A history of sexually transmitted diseases, particularly gonorrhea in the last six months, was also associated with an increased risk of HIV infection.