Nonoccupational postexposure prophylaxis, subsequent risk behaviour and HIV incidence in a cohort of Australian homosexual men
ABSTRACT To investigate the relationship between nonoccupational postexposure prophylaxis (NPEP) use and future HIV risk behaviours and HIV infection in a cohort of HIV-negative homosexual men in Sydney, Australia.
Prospective analysis of NPEP use in a community cohort from 2001 to 2007.
In the Health in Men study cohort, men were annually questioned about NPEP use and tested for HIV. Every 6 months, detailed quantitative data on unprotected anal intercourse were collected. Cox regression models examined risk factors for incident NPEP use, HIV seroconversion and time trends in NPEP use. The change in the number of unprotected anal intercourse acts with nonseroconcordant partners before and after NPEP was examined using the Wilcoxon signed-rank test.
One thousand four hundred and twenty-seven participants were enrolled. At baseline, 78.5% of participants had heard of NPEP, which increased to 97.4% by the fifth annual interview. NPEP use increased significantly from 2.9 per 100 person-years in 2002 to 7.1 per 100 person-years in 2007 (P = 0.007). Unprotected anal intercourse was a strong predictor of incident NPEP use. Use of NPEP was not associated with changes in HIV risk behaviour. Men who received NPEP had a significantly higher rate of subsequent HIV seroconversion (hazard ratio 2.67, 95% confidence interval 1.40-5.08, P = 0.003).
Awareness of the availability of NPEP in this cohort was nearly universal. Use was common and increased rapidly over the study period. NPEP was targeted mostly towards high-risk behaviours. Use of NPEP was not associated with reductions in risk behaviour, and men who received NPEP continued to be at high risk of subsequent HIV infection.
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ABSTRACT: 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, 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 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.HIV Medicine 04/2010; 11(10):635-41. DOI:10.1111/j.1468-1293.2010.00833.x · 3.45 Impact Factor