HIV-negative gay men in Sydney, Australia, are increasingly selecting other HIV-negative men for unprotected casual anal sex, according to a study published in the May 15th edition of AIDS. The practice of deliberately selecting partners of the same HIV status – often called “serosorting” – has been well described amongst HIV-positive gay men and even been credited with contributing to a fall in HIV incidence in San Francisco. However, investigators from Sydney caution that serosorting by men who assume that they are HIV-negative is “highly problematic.”
A separate study published in the same edition of AIDS found that the proportion of gay men reporting unprotected anal sex with a casual partner increased in Sydney between 1999 and 2002, but that optimism about HIV therapy could not explain this change in sexual behaviour.
Serosorting
Serosorting amongst gay men has been defined as “discussing HIV status with potential partners and only engaging in HIV risk behaviour with those they believe are of a similar HIV status.” Most investigators have looked at the serosorting behaviours of HIV-positive men and there are limited data on serosorting amongst HIV-negative gay men. There is also some evidence from the United States that HIV-negative men are increasingly avoiding sex with men who know they are HIV-positive.
Investigators from Sydney therefore looked at the serosorting behaviour of gay men known to be HIV-negative between 2002 and 2005. Although these men were not explicitly asked if they had “serosorted,” this behaviour was inferred from information they provided about unprotected sex with casual partners.
The 302 men enrolled in the study were asked to provide details of the total number of casual partners they had unprotected anal sex with in the previous six months, and to provide information on their partner’s HIV infection status.
Although there was an overall decrease in the amount of unprotected anal sex with casual partners in the six months before the study interview, the investigators noted that when they looked at the results according to the HIV status of casual partners, the mean number of HIV-negative casual partners who individuals had sex with actually increased (p
“Serosorting…especially is used as a deliberate strategy to replace consistent condom use with casual partners, is highly problematic”, write the investigators. They note that even if both partners are indeed HIV-negative there is still the risk of other sexually transmitted infections.
What’s more, HIV status is sometimes assumed rather than actually known. In addition, the investigators believe that it is “unrealistic” to expect all men to honestly disclose their HIV status. Finally, the investigators note that discussions leading to the initiation of unprotected sex are often “implied or inferred” rather than verbal or face-to-face. They also suggest that the internet may have a role in the apparent increase in serosorting.
More unsafe sex, but HIV optimism not an explanation
A separate study looked at the role of HIV optimism in changes in gay men’s sexual behaviour in Sydney between 1999 and 2002. The study involved over 3,000 men aged from their late teens to their 70s. They were asked to say if they had had unprotected anal sex with a casual partner in the last six months.
HIV optimism was assessed by responses to four statements: “New HIV treatments take the worry out of sex”; “The availability of treatment immediately after unsafe sex makes safe sex less important”; “HIV is less of a threat because the epidemic is on the decline”; and, “HIV/AIDS is a less serious threat than it used to be because of new treatments.”
Between 1999 and 2002 there was a significant increase in the number of men reporting unprotected sex with a casual partner from 32 to 41% (p
In further analysis, the investigators observed that HIV-positive men were more likely than other men (58% vs. 31%, p
“It is noteworthy that HIV optimism…remained essentially constant over time”, write the investigators, adding, “if HIV optimism did explain the increase in sexual risk over time, either year of survey would remain significant in the multivariate analysis or there would be a significant interaction between year of survey and optimism. Neither of these was the case.” Therefore, although HIV optimism was related to unprotected sex, it could not explain the increased number of men reporting unprotected sex over time.
Mao L et al. ”Serosorting” in casual anal sex of HIV-negative gay men is noteworthy and is increasing in Sydney, Australia. AIDS 20: 1204-1206, 2006.
Abelson J et al. HIV optimism does not explain increases in high-risk sexual behaviour among gay men of positive or negative HIV status in Sydney, Australia. AIDS 20: 1215-1216, 2006.