Gay men in Sydney who only have unprotected anal intercourse as part of a risk reduction strategy such as serosorting or negotiated safety have a considerably lower risk of acquiring HIV than men who have unprotected sex in other ways, report Australian researchers in the January 14th issue of AIDS.
Men who have unprotected anal intercourse only as the insertive partner, and those who ensure that their partner withdraws before ejaculation, also had a lower risk of acquiring HIV than men who don't employ any form of risk reduction strategy when they have unprotected anal intercourse.
Taken together, men using any of these practices were three times more likely to acquire HIV than men who had no unprotected anal intercourse (UAI). However men who practiced UAI without any of these safeguards were almost eleven times more likely than men having no UAI to acquire HIV.
Moreover, withdrawal before ejaculation was the riskiest practice studied. It was associated with a five fold increase in the risk of infection (compared to no UAI).
These strategies have been used by gay men for many years and some scientists consider them to be biologically plausible, but until now there has been limited evidence on their effectiveness in the real world. One important study came in 2007 when Fengyi Jin reported that a third of Australian gay seroconverters had tried to employ a risk reduction strategy.
The new research has once again been conducted by Fengyi Jin and his colleagues at the University of South Wales. The methods are different however – for this prospective study, 1,427 HIV negative homosexually active men in Sydney were recruited to the HIM (Health in Men) cohort. Participants were interviewed twice a year and were tested for HIV infection once a year. The average time men stayed in the study was just under four years.
At each interview men were asked to recall their sexual behaviour since the last interview. Rather than use terms such as ‘negotiated safety’ or describe intentions, the participants were asked detailed questions about their sexual practice. The researchers used this information to put men into groups according to their recent behaviour.
- Serosorting - reporting that any unprotected sex during the study period was with partners that the study participant believed to be HIV-negative. The sex could be with casual or regular partners. This behaviour was reported by men at 38% of interviews.
- Negotiated safety - a specific form of serosorting with a primary regular partner. Criteria included having a clear spoken agreement that unprotected sex was not permitted outside the relationship and mutual disclosure of the most recent HIV test results. Men described this practice at 25% of interviews.
- Strategic positioning - only having unprotected anal intercourse (UAI) as the insertive partner. This was described at 15% of interviews.
- Withdrawal - men reporting receptive UAI, but in each case their partner had not ejaculated inside them. Men reported this practice at 13% of interviews.
Only men who used a strategy consistently during the six month period would be assigned to that group - for example a man who almost always had insertive UAI but did have a single episode of receptive UAI would not be considered to practice ‘strategic positioning’.
During the course of the study, 53 men seroconverted to HIV, an overall incidence of 0.78 per 100 person years.
It’s important to note that because the number of infections was relatively small, some of the results do not reach statistical significance and the confidence intervals are often very wide.
(In other words, some results could be due to chance alone. The 95% confidence interval gives a range of figures, and it is thought that the ‘true’ result is likely to be within the range. For example, for someone practicing a particular behaviour, there may be five times the risk of acquiring HIV, with a confidence interval of 4.0-6.0. This means that the real figure could be anywhere between four times and six times the risk. However if the confidence interval was 0.5-24.0, the range of possible results would be so wide as to be meaningless.)
Compared to men who reported no UAI at all, men practicing serosorting appear in the raw data to be twice as likely to acquire HIV (hazard ratio 2.2). However as the confidence interval is 0.9 - 5.4 and drops below 1, the result is not statistically significant: it could also be the case that serosorters were actually less likely to acquire HIV.
The results for negotiated safety and strategic positioning were broadly similar. The hazard ratios were 1.7 and 1.5 respectively, but the confidence intervals were wide and dropped below 1.
The results for withdrawal are more clear cut. Compared to men who had no unprotected sex, men using this strategy were five times as likely to acquire HIV (hazard ratio 5.0, confidence interval 1.9 - 12.9). Nonetheless, the authors note this increased risk may be partly attributed to men primarily employing the strategy when with HIV-positive partners.
However, when all risk reduction strategies were grouped together, men using them were three times as likely to acquire HIV as men who had no UAI (hazard ratio 3.0, confidence interval 1.3 - 6.9).
Nonetheless, the risk reduction practices were considerably safer than having UAI without those safeguards. Men with other patterns of UAI were almost eleven times likely to acquire HIV as men who had no UAI (hazard ratio 10.8, confidence interval 4.3 - 27.2). More specifically, those who had unprotected sex with men of unknown or positive status were more likely to seroconvert than those who serosorted. Similarly, men who had unprotected receptive sex were at greater risk than men who only had insertive sex.
The degree of protection can also be shown by looking specifically at men who reported some unprotected anal intercourse with HIV-positive partners. Once again compared to men who had no UAI at all, men only having insertive UAI were nine times more likely to acquire HIV, men whose partners practiced withdrawal were ten times more likely, but men whose partners ejaculated inside them were sixty-five times more likely to be infected.
Fengyi Jin and his colleagues state that “each of the risk reduction behaviours examined was associated with a HIV incidence that was intermediate between that in those who reported no UAI, and UAI without that form risk reduction behaviour”. They argue that each risk reduction behaviour offers “substantial but incomplete protection against HIV infection”.
They recommend that policy makers, educators and researchers “engage with the realities under which UAI is occurring”.
They also note that Sydney is one of the few places in the developed world that has not had recent increases in HIV diagnoses in gay men, and that incidence was relatively low in this study, despite high overall levels of unprotected sex. They believe this suggests that “risk reduction behaviours can be associated with some success in containing HIV at the population level”.
In an accompanying editorial, Fritz van Griensven of the Centers for Disease Control and Prevention suggests that some of the specific characteristics of the gay community in Sydney may have allowed for this success. Specifically, the rate of HIV testing is one of the highest in the world, allowing accurate knowledge of HIV status. Moreover, a strong gay community may have helped reduce stigma and discrimination, making disclosure of status more likely.
He notes that this is not the case in many other settings, and urges caution in generalising these findings for use in HIV prevention programmes elsewhere.
Jin F et al. Unprotected anal intercourse, risk reduction behaviours, and subsequent HIV infection in a cohort of homosexual men. AIDS 23: 243-52, 2009.
Van Griensven F. Non-condom use risk-reduction behaviours: can they help to contain the spread of HIV infection among men who have sex with men? AIDS 23: 253-5, 2009.