Undetectable viral load associated with unprotected sex amongst HIV discordant gay couples in Sydney

An undetectable viral load is associated with unprotected anal sex amongst HIV serodiscordant gay couples in Sydney, according to a study published in the January 28^th edition of AIDS. However, the investigators also established that the majority of gay men involved in serodiscordant relationships do not have unprotected sex, and an editorial accompanying the study notes that a large meta-analysis of studies examining sexual risk taking in the HAART era failed to find any association between an undetectable viral load and an increased risk of unprotected sex.

Since the introduction of HAART in the late 1990s there have been reports from the US, UK, Europe and Australia of an increase in unprotected anal sex amongst gay men. It has been suggested that increases in sexual risk taking by gay men have been attributed to treatment optimism about the effectiveness of HAART, particularly its ability to lower the infectiousness of an HIV-positive individual. However there are conflicting data from studies which have investigated this.

Accordingly, investigators in Sydney examined the relationship between self-reported viral load and sexual risk taking within HIV discordant gay couples. The men were recruited from two cohorts: the Health in Men cohort of HIV-negative men, and the Positive Health cohort of HIV-positive men. The men provided study information at face-to-face interviews between July 2001 and December 2003.

Study design

The men reported numbers of regular and causal partners in the previous six months, and the HIV status of their current regular partner. They were also asked to say if they had unprotected anal sex with their casual or regular partner, and if so if they were insertive or receptive, and if ejaculation occurred inside.

HIV-positive men were asked to report the results of their latest viral load test. Viral load was divided by the investigators into one of four categoies: undetectable (below 500 copies/ml); low (below 10,000 copies/ml), moderate (10,000 – 50,000 copies/ml) and high (above 50,000 copies/ml). HIV-negative men were asked to report the viral load of their HIV-positive partner, using the same four categories.

In addition, both HIV-positive and HIV-negative men completed an eleven item questionnaire designed to assess their HIV optimism.

Results

A total of 45 HIV-negative men and 74 HIV-positive men were included in the investigators’ analysis, providing data for 119 HIV serodiscordant couples.

In 21% of relationships, there was no anal sex, and 48% reported only having anal sex with condoms. However, in the remaining 31% of relationships, the men had unprotected anal sex.

Unprotected anal sex was significantly more likely when viral load was undetectable (39% versus 21%, p = 0.04). In multivariate analysis, the investigators found that younger age (p = 0.05), and greater HIV optimism (p = 0.02) were also significantly associated with unprotected anal sex in serodiscordant relationships.

Even when unprotected anal sex was occurring within serodiscordant relationships, the investigators found that men were attempting to manage the risk of HIV transmission. Eleven of the 15 (73%) HIV-negative men who were having unprotected anal sex said that their HIV-positive partner never ejaculated inside. Of the eleven HIV-positive men who said that they had unprotected anal sex with their partner, eight (73%), said they never ejaculated inside their HIV-negative partner.

There were only eleven men in HIV serodiscordant relationships in which the HIV-positive man had a detectable viral load and the men had unprotected anal sex. Three of the men were HIV-negative, the other eight HIV-positive. All three of the HIV-negative men said that their partner never ejaculated inside, and five of the HIV-positive men said that they never ejaculated inside their HIV-negative partner.

“Most HIV serodiscordant gay couples in Sydney…do not engage in unprotected anal intercourse within their relationship”, stress the investigators in the discussion of their research. They add, “where they do, unprotected anal intercourse in HIV serodiscordant gay relationships is associated with reporting that the HIV-positive partner has an undetectable viral load.”

The investigators conclude, “given that gay men in HIV serodiscordant relationships are incorporating clinical information in their sexual practice, it is important that they are made aware of how transmission risks, viral load variability and drug-resistant strains of HIV may relate to their specific situation.”

The bigger picture

An editorial accompanying the Sydney study notes that it “contributes further to our understanding of the role of HAART in relation to sexual behaviour. On the face of it, their paper suggests that having a reduced viral load may trigger risky sexual behaviour among HIV-positive gay men.” However, the authors of the editorial note that a recent systematic review of papers examining HAART and sexual risk taking failed to find any significant relationship between having an undetectable viral load and sexual risk taking. “Speculation that taking HAART or having an undetectable viral load might trigger risky behaviour among people with HIV is not therefore supported by these meta-analyses” stress the authors, who add “it would appear, therefore, that the recent increase in high-risk sexual behaviour among HIV-positive men can not be attributed to taking HAART or having an undetectable viral load per se.

However, the editorial notes that HAART optimism was found to be related to risk taking in the recent review of studies, but again do not believe that this can account, on its own, for recent shifts in the sexual behaviour of gay men. They note that several studies have found that only a minority of gay men believe that HAART reduces the risk of HIV transmission. “At a population level…it is unlikely that these beliefs alone can explain the increase in high-risk behaviour among HIV-positive as well as HIV-negative men since 1996.”