Impact of highly active antiretroviral treatment on HIV seroincidence among men who have sex with men: San Francisco.

OBJECTIVES

This study assessed the countervailing effects on HIV incidence of highly active antiretroviral treatment (HAART) among San Francisco men who have sex with men (MSM).

METHODS

Behavioral risk was determined on the basis of responses to cross-sectional community interviews. HIV incidence was assessed through application of an enzyme-linked immunoassay testing strategy.

RESULTS

Use of HAART among MSM living with AIDS increased from 4% in 1995 to 54% in 1999. The percentage of MSM who reported both unprotected anal intercourse and multiple sexual partners increased from 24% in 1994 to 45% in 1999. The annual HIV incidence rate increased from 2.1% in 1996 to 4.2% in 1999 among MSM who sought anonymous HIV testing, and the rate was high (5.3%) but stable in a blinded survey of MSM seeking sexually transmitted disease services.

CONCLUSIONS

Any decrease in per contact risk of HIV transmission due to HAART use appears to have been counterbalanced or overwhelmed by increases in the number of unsafe sexual episodes.