Nonoccupational PEP, Subsequent Risk Behavior and HIV Incidence in a Cohort of Australian Homosexual Men

Published: June 1, 2009

Nonoccupational Postexposure Prophylaxis, Subsequent Risk Behavior and HIV Incidence in a Cohort of Australian Homosexual Men


The current prospective analysis investigated the relationship between nonoccupational postexposure prophylaxis (NPEP) use, future risk behaviors, and HIV infection in a cohort of HIV-negative homosexual men in Sydney. Participants in the Health in Men study were questioned annually about NPEP use and tested for HIV infection. Every six months, researchers collected detailed quantitative data on unprotected anal intercourse. Cox regression models were used to examine risk factors for incident NPEP use, HIV seroconversion, and NPEP use time trends. The Wilcoxon signed-rank test was used to examine the change in the number of unprotected anal intercourse acts with nonserodiscordant partners before and after NPEP. A total of 1,427 participants were enrolled. The proportion of men who had heard of NPEP was 78.5 percent at baseline and 97.4 percent 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. NPEP use was not associated with changes in HIV risk behavior. NPEP users had a significantly higher rate of subsequent HIV seroconversion (hazard ratio 2.67, 95 percent confidence interval 1.40-5.08, P=0.003). “Awareness of the availability of NPEP in this cohort was nearly universal,” the authors concluded. “Use was common and increased rapidly over the study period. NPEP was targeted mostly towards high-risk behaviors. Use of NPEP was not associated with reductions in risk behavior, and men who received NPEP continued to be at high risk of subsequent HIV infection.”

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