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Thursday, May 11, 2006 - 8:30 AM
344

Major determinant of recent increases in HIV incidence among men who have sex with men in British Columbia: deferred initiation of antiretroviral therapy

Thomas M. Lampinen1, Rebecca Baggaley2, Geoff Garnett2, Keith Chan3, Nada Gataric3, Julio Montaner3, and Robert Hogg3. (1) British Columbia Centre for Excellence in HIV/AIDS, University of British Columbia, BC Centre for Excellence in HIV/AIDS, 608-1081 Burrard Street, Vancouver, BC, Canada, (2) Imperial College London, London, (3) British Columbia Centre for Excellence in HIV/AIDS, Vancouver, BC


Background:
Recent guidelines endorse deferral of HAART until later in the course of HIV infection. The effect of this change on population levels of high viremia, infectivity and sexual transmission of HIV is unknown

Objective:
Describe populational trends in HIV viremia among MSM in BC in relation to a 1999 change that deferred HAART to CD4<200 cells/mL. Estimate relative increases in new HIV diagnoses among MSM attributable to this change.


Method:
Linked provincial registries provided records of all HAART, CD4 cell counts, and plasma HIV RNA viral load (pVL) determinations from 1997-2003. We assessed trends in MSM with viremia (pVL >10 000 copies per ml) across 6-month intervals. Mathematical models predicted relative changes in infections among MSM following introduction and deferral of HAART.

Result:
.The number and proportion of highly viremic MSM declined steadily [from 443 (27.6%)] for two years following introduction of HAART. This trend reverted, increasing from 358 viremic MSM (17.8%) in the second half of 1999 to 713 (26.7%) at the end of 2003; this increase occurred among men with CD4>200. Models predict a 50% reduction in HIV diagnoses among MSM from 1997-1999, then a rapid 83% increase following HAART deferral.

Conclusion:
HAART deferral appears to be a major determinant of the 75% increase in new infections among MSM observed in BC from 1999 to 2004.

Implications:
HAART deferrals affect incidence, warranting substantial increases in HIV prevention among MSM.

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