A survey of young gay men and transgender women in Bangkok has found that HIV incidence is running at 9% a year in those who don’t use condoms consistently – and 2% a year in those who say they do.
The survey also found higher-than-average incidence in respondents who lived alone or with flatmates rather than their family, and who had paid-for sex or sex in saunas.
In common with at least one other study, the researchers found that men who have sex with men (MSM) who exclusively took the insertive role in sex – regardless of condom use - were less likely to become HIV-positive than MSM who said they used condoms all the time.
Presenter Presenter Tarika Pattanasin of the Thai Ministry of Public Health told the 20th International AIDS Conference that a previous analysis of the Bangkok MSM Cohort Study had shown that HIV incidence in young gay men and transgender women aged 18-21 was 8.8% a year, compared with 3.7% a year in MSM aged over 30.
A new analysis concentrated exclusively on young MSM who had been 18-24 at their time of enrolment into the cohort between 2006 and 2010. This allows for between three and five years of follow-up.
Criteria for entry into this study other than age included residence in Bangkok, having had sex (oral or anal) with another man in the last six months and being available for thrice-yearly HIV testing and behavioural questionnaires. The cohort recruited 494 men through gay venues, the internet, a gay men’s sexual health clinic, outreach workers and friends.
The study found that 47% of the young men/transgender women lived with their family while 44% lived alone or with a flatmate and just 10% lived with a partner.
Forty per cent said that they had used condoms 100% of the time for anal sex since their last clinic visit four months ago, 51% had had condomless anal sex and been ‘versatile’ (took both roles) or ‘bottom’ (receptive only); 8.5% said they had had condomless sex but only as the insertive partner.
Twenty-four per cent said they had had paid-for sex in the last four months and 28% casual sex in a sauna; 33% had Had sex with casual partner at home.
The results were expressed as the cumulative number of HIV infections over a specific time period or ‘incidence density’. A large number of longer-term participants was tested around the five-year anniversary of their entry into the cohort, so this provides a useful cumulative incidence measure.
The overall annual incidence rate in the cohort was 7.5% a year and 118 people have acquired HIV so far in this study; nearly a quarter of the cohort.
By the five-year mark, roughly 39% of those who lived alone or with a flatmate had become HIV positive compared with 19% who was living with their family at this point (NB these categories all apply to the four months preceding each follow-up visit – they are not baseline criteria. So if someone reported living alone for one four-month period, but living with family the next, for example, they would be sorted into different risk groups for those two separate time periods.)
About 45% of those who reported paid-for sex was HIV-positive by this time compared with 22% who did not. And the same proportion – 45% - who reported casual sex, either in a sauna or at home, had HIV compared with 21% who did not have casual sex.
In terms of sexual behaviour, men who reported condomless anal sex, either as the receptive partner or as ‘versatile’, had a 46% chance of HIV infection by five years; men who reported 100% consistent condom use had a 21% chance of having HIV by this time; and men who reported condomless sex, but only as the insertive partner, had a 14% chance of being HIV positive by this time.
Thus, in unadjusted analysis, self-reported 100% condom use was 54% effective as a preventative strategy against HIV in this cohort, and not taking the receptive role 70% effective.
In multivariate analysis people who lived alone or with a flatmate were 50% more likely to acquire HIV than those who lived with their family; those who did not or only inconsistently used condoms and who took the receptive role at least sometimes were 180% (2.8 times) more likely to acquire HIV than those who maintained condom use 100% of the time; those who only took the insertive role, regardless of condom use, were 20% less likely than those who used condoms 100% of the time but were not always ‘top’, though in multivariate analysis, controlling for factors like number of partners, this difference became statistically non-significant.
Also in multivariate analysis, having paid-for sex increased the risk of HIV 120%, having casual sex in a sauna 90%, and having casual sex 60% more risky for HIV than not paying for sex or not having casual sex.
It’s important to remember that the MSM at highest risk in this study – the receptive or versatile inconsistent condom users - actually formed the majority of the men in the cohort.
What can we do to prevent HIV in such a relentlessly accumulating epidemic, which is by no means unique to Thailand?
Luiz Loures of UNAIDS, who was chairing the session, commented: “It is a huge problem that young gay men today are coming out into a population where already a much higher proportion of their contemporaries has HIV than was the case 20 years ago.”
No one single measure would probably contain HIV in such a situation. The Thai Red Cross, who run the largest HIV clinic in Bangkok, are setting their sights on trying to get MSM to test as frequently as possible in the hope of catching early infections; this is the inspiration behind the ‘Suck. F***. Test. Repeat.’ campaign which has garnered praise for its videos but also criticism for not including condom use in its text.
Dr Sarika said that a campaign helping young MSM not to engage in commercial sex was also being considered. She acknowledged that this was a population that PrEP might be considered for.
Thienkrua W, Pattanasin S (presenter) et al. Incidence and risk factors of HIV infection among young men who have sex with men (YMSM) - Bangkok, Thailand. 20th International AIDS Conference, Melbourne. Abstract THAC0202. 2014.