“
“The aim of the

study was to assess whether subpopulations with sufficiently high HIV incidences for HIV prevention trials can be identified in low HIV incidence settings such as Australia. In a community-based cohort study of HIV-negative homosexually active men in Sydney, Australia, AC220 potential risk factors associated with an annual HIV incidence of ≥2 per 100 person-years (PY) were identified. A stepwise procedure ranked these factors according to HIV incidence, to create a ‘high-incidence’ subgroup of participants. Willingness to participate in HIV prevention trials was assessed. Although the incidence in the cohort overall was only 0.78 per 100 PY, nine risk variables were associated with an HIV incidence of 2 per 100 PY or greater. Stepwise inclusion of these variables revealed a ‘high-incidence’ subgroup of men representing 24% of the total follow-up time with a combined HIV incidence of 2.71 per 100 PY, who reported at least Verteporfin clinical trial one of three risk factors in the past 6 months. These men were more willing than others to participate in vaccine and antiretroviral therapy HIV prevention trials. These findings demonstrate that it is possible to identify high HIV incidence subpopulations in low-incidence settings such as

Australia, and these men are of above average willingness to participate in HIV prevention trials. A range of biomedical HIV Linifanib (ABT-869) prevention technologies are under clinical development, including vaginal and rectal microbicides, pre-exposure prophylaxis (PREP) and vaccines [1]. A number of these agents have reached the stage of large-scale effectiveness trials [2,3]. It is generally accepted that to measure

the effectiveness of the prevention intervention with adequate power and achievable sample sizes, such trials require populations with high HIV incidences of around 2% or more per year [4,5]. Most communities with a high incidence of HIV infection are found in resource-poor countries. There is an urgent need for prevention interventions in these settings, where the social, economic and public health consequences of the HIV pandemic have been enormous. For these reasons, the focus of many HIV intervention trials has moved to the developing world [5]. All published vaginal microbicide [6–15] and PREP effectiveness trials [16] and almost all ongoing trials have been conducted solely in resource-poor countries [2,3]. HIV vaccine trials, in contrast, have generally been conducted in both resource-rich and resource-poor countries [17–20]. There are only a small number of communities in resource-rich settings where the HIV incidence is higher than 2% per year. In Australia, the incidence of HIV infection is relatively low, and among men who have sex with men (MSM), the group most affected by HIV, the incidence is <1% [21].