Abstract 224 - Post-Exposure Prophylaxis (PEP) for Sexual Exposure to HIV Does Not Lead to Increases in High Risk Behavior: The San Francisco PEP Project.

224 Post-Exposure Prophylaxis (PEP) for Sexual Exposure to HIV Does Not Lead to Increases in High Risk Behavior: The San Francisco PEP Project.

J. N. Martin*, M. E. Roland, J. D. Bamberger, M. A. Chesney, J. O. Kahn, T. J. Coates, and M. H. Katz.
Univ. of California, San Francisco and San Francisco Dept. of Publ. Hlth..

Background:The efficacy of PEP following occupational HIV exposure has prompted advocacy for PEP following non-occupational sexual or drug use exposure. It is not known, however, whether provision of PEP for non-occupational exposures may perversely lead to increases in risk-taking behavior and potentially increased HIV incidence, particularly among high-risk groups like men who have sex with men (MSM).

Methods:Persons reporting sexual (receptive or insertive anal or vaginal intercourse, or receptive oral intercourse with ejaculation) or injection drug use exposures to HIV within the prior 72 hrs were provided 4 weeks of antiretroviral medication and risk reduction counseling. Subjects were asked about their prior 3-month high-risk behavior at baseline and then at 6 and 12 months post-exposure and were monitored for HIV seroconversion for 1 year.

Results:Of 401 participants receiving PEP, 379 presented with a sexual exposure, of whom 336 were MSM. Among MSM, at 6 months post-exposure, 74% reported a decrease, compared to baseline, in the number of times they had performed unprotected receptive or insertive anal intercourse or receptive oral intercourse with ejaculation with a high-risk partner; 16% reported no change, and 9.6% had an increase. At 12 months, 72% reported a decrease in high-risk activity compared to baseline, 14% had no change, and 14% had an increase. By 12 months, 17% (95% CI: 13—21%) of MSM were treated with at least one other course of PEP for a repeat exposure; 9 persons were treated twice, 5 three times, and 1 four times. Three MSM seroconverted for HIV (none associated with the presenting exposure) for a rate of 1.2/100 p-y (95% CI: 0.3—3.1), equivalent to current rates estimated in San Francisco among MSM.

Conclusion:After receipt of PEP, most MSM do not experience behavioral disinhibition. Instead, most exhibit a decrease in high-risk behavior. That an increase in risk-taking behavior does occur in some men, although not definitively attributable to availability of PEP, nevertheless indicates the need to prospectively identify these men and develop an intensive behavioral intervention to prevent repeat exposures.